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QUESTION

IntelliJ - Invalid source release: 17

Asked 2022-Mar-17 at 13:46

I've created a new Java project in IntelliJ with Gradle that uses Java 17. When running my app it has the error Cause: error: invalid source release: 17.

My Settings

I've installed openjdk-17 through IntelliJ and set it as my Project SDK.

The Project language level has been set to 17 - Sealed types, always-strict floating-point semantics.

enter image description here

In Modules -> Sources I've set the Language level to Project default (17 - Sealed types, always strict floating-point semantics).

modules->sources

In Modules -> Dependencies I've set the Module SDK to Project SDK openjdk-17.

modules->dependencies

In Settings -> Build, Execution, Deployment -> Compiler -> Java Compiler I've set the Project bytecode version to 17.

enter image description here

Gradle

1plugins {
2    id 'org.springframework.boot' version '2.5.6'
3    id 'io.spring.dependency-management' version '1.0.11.RELEASE'
4    id 'java'
5}
6
7group = 'com.app'
8version = '0.0.1-SNAPSHOT'
9sourceCompatibility = '17'
10
11repositories {
12    mavenCentral()
13}
14
15dependencies {
16    implementation 'org.springframework.boot:spring-boot-starter-web'
17    implementation 'org.springframework.boot:spring-boot-starter-websocket'
18    testImplementation 'org.springframework.boot:spring-boot-starter-test'
19    implementation 'com.fasterxml.jackson.core:jackson-core:2.13.0'
20    implementation 'com.fasterxml.jackson.core:jackson-databind:2.13.0'
21}
22
23test {
24    useJUnitPlatform()
25}
26

I've looked at all of the answers here but I can't seem to fix this. I must be missing something but I can't find it. I've not had any problems using Java 8 or 11.

How do I resolve this?

ANSWER

Answered 2021-Oct-24 at 14:23

The message typically entails that your JAVA_HOME environment variable points to a different Java version.

Here are the steps to follow:

  • Close IntelliJ IDEA
  • Open a terminal window and check your JAVA_HOME variable value:
    • *nix system: echo $JAVA_HOME
    • Windows system: echo %JAVA_HOME%
  • The JAVA_HOME path should be pointing to a different path, then set it to the openjdk-17 path:
    • *nix system: export JAVA_HOME=/path/to/openjdk-17
    • Windows system: set JAVA_HOME=path\to\openjdk-17
  • Open your project again in IntelliJ IDEA
  • Make sure to set both source and target compatibility versions (not only the sourceCompatibility)

You should be able to build your project.

EDIT: Gradle Toolchain

You may need also to instruct Gradle to use a different JVM than the one it uses itself by setting the Java plugin toolchain to your target version:

1plugins {
2    id 'org.springframework.boot' version '2.5.6'
3    id 'io.spring.dependency-management' version '1.0.11.RELEASE'
4    id 'java'
5}
6
7group = 'com.app'
8version = '0.0.1-SNAPSHOT'
9sourceCompatibility = '17'
10
11repositories {
12    mavenCentral()
13}
14
15dependencies {
16    implementation 'org.springframework.boot:spring-boot-starter-web'
17    implementation 'org.springframework.boot:spring-boot-starter-websocket'
18    testImplementation 'org.springframework.boot:spring-boot-starter-test'
19    implementation 'com.fasterxml.jackson.core:jackson-core:2.13.0'
20    implementation 'com.fasterxml.jackson.core:jackson-databind:2.13.0'
21}
22
23test {
24    useJUnitPlatform()
25}
26// build.gradle
27java {
28    toolchain {
29        languageVersion = JavaLanguageVersion.of(17)
30    }
31}
32

Source https://stackoverflow.com/questions/69696321

QUESTION

The transaction declared chain ID 5777, but the connected node is on 1337

Asked 2022-Mar-11 at 02:52

I am trying to deploy my SimpleStorage.sol contract to a ganache local chain by making a transaction using python. It seems to have trouble connecting to the chain.

1from solcx import compile_standard
2from web3 import Web3
3import json
4import os
5from dotenv import load_dotenv
6
7load_dotenv()
8
9with open("./SimpleStorage.sol", "r") as file:
10    simple_storage_file = file.read()
11
12compiled_sol = compile_standard(
13    {
14        "language": "Solidity",
15        "sources": {"SimpleStorage.sol": {"content": simple_storage_file}},
16        "settings": {
17            "outputSelection": {
18                "*": {"*": ["abi", "metadata", "evm.bytecode", "evm.sourceMap"]}
19            }
20        },
21    },
22    solc_version="0.6.0",
23)
24
25with open("compiled_code.json", "w") as file:
26    json.dump(compiled_sol, file)
27
28
29# get bytecode
30bytecode = compiled_sol["contracts"]["SimpleStorage.sol"]["SimpleStorage"]["evm"][
31    "bytecode"
32]["object"]
33
34
35# get ABI
36abi = compiled_sol["contracts"]["SimpleStorage.sol"]["SimpleStorage"]["abi"]
37
38# to connect to ganache blockchain
39w3 = Web3(Web3.HTTPProvider("HTTP://127.0.0.1:7545"))
40chain_id = 5777
41my_address = "0xca1EA31e644F13E3E36631382686fD471c62267A"
42private_key = os.getenv("PRIVATE_KEY")
43
44
45# create the contract in python
46
47SimpleStorage = w3.eth.contract(abi=abi, bytecode=bytecode)
48
49# get the latest transaction
50nonce = w3.eth.getTransactionCount(my_address)
51
52# 1. Build a transaction
53# 2. Sign a transaction
54# 3. Send a transaction
55
56
57transaction = SimpleStorage.constructor().buildTransaction(
58    {"chainId": chain_id, "from": my_address, "nonce": nonce}
59)
60print(transaction)
61
62

It seems to be connected to the ganache chain because it prints the nonce, but when I build and try to print the transaction here is the entire traceback call I am receiving

1from solcx import compile_standard
2from web3 import Web3
3import json
4import os
5from dotenv import load_dotenv
6
7load_dotenv()
8
9with open("./SimpleStorage.sol", "r") as file:
10    simple_storage_file = file.read()
11
12compiled_sol = compile_standard(
13    {
14        "language": "Solidity",
15        "sources": {"SimpleStorage.sol": {"content": simple_storage_file}},
16        "settings": {
17            "outputSelection": {
18                "*": {"*": ["abi", "metadata", "evm.bytecode", "evm.sourceMap"]}
19            }
20        },
21    },
22    solc_version="0.6.0",
23)
24
25with open("compiled_code.json", "w") as file:
26    json.dump(compiled_sol, file)
27
28
29# get bytecode
30bytecode = compiled_sol["contracts"]["SimpleStorage.sol"]["SimpleStorage"]["evm"][
31    "bytecode"
32]["object"]
33
34
35# get ABI
36abi = compiled_sol["contracts"]["SimpleStorage.sol"]["SimpleStorage"]["abi"]
37
38# to connect to ganache blockchain
39w3 = Web3(Web3.HTTPProvider("HTTP://127.0.0.1:7545"))
40chain_id = 5777
41my_address = "0xca1EA31e644F13E3E36631382686fD471c62267A"
42private_key = os.getenv("PRIVATE_KEY")
43
44
45# create the contract in python
46
47SimpleStorage = w3.eth.contract(abi=abi, bytecode=bytecode)
48
49# get the latest transaction
50nonce = w3.eth.getTransactionCount(my_address)
51
52# 1. Build a transaction
53# 2. Sign a transaction
54# 3. Send a transaction
55
56
57transaction = SimpleStorage.constructor().buildTransaction(
58    {"chainId": chain_id, "from": my_address, "nonce": nonce}
59)
60print(transaction)
61
62Traceback (most recent call last):
63File "C:\Users\evens\demos\web3_py_simple_storage\deploy.py", line 
6452, in <module>
65transaction = SimpleStorage.constructor().buildTransaction(
66File "C:\Python310\lib\site-packages\eth_utils\decorators.py", line 
6718, in _wrapper
68return self.method(obj, *args, **kwargs)
69File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
70packages\web3\contract.py", line 684, in buildTransaction
71return fill_transaction_defaults(self.web3, built_transaction)
72File "cytoolz/functoolz.pyx", line 250, in 
73cytoolz.functoolz.curry.__call__
74return self.func(*args, **kwargs)
75File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
76packages\web3\_utils\transactions.py", line 114, in 
77fill_transaction_defaults
78default_val = default_getter(web3, transaction)
79File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
80packages\web3\_utils\transactions.py", line 60, in <lambda>
81'gas': lambda web3, tx: web3.eth.estimate_gas(tx),
82File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
83packages\web3\eth.py", line 820, in estimate_gas
84return self._estimate_gas(transaction, block_identifier)
85File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
86packages\web3\module.py", line 57, in caller
87result = w3.manager.request_blocking(method_str,
88File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
89packages\web3\manager.py", line 197, in request_blocking
90response = self._make_request(method, params)
91File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
92packages\web3\manager.py", line 150, in _make_request
93return request_func(method, params)
94File "cytoolz/functoolz.pyx", line 250, in 
95cytoolz.functoolz.curry.__call__
96return self.func(*args, **kwargs)
97File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
98packages\web3\middleware\formatting.py", line 76, in 
99apply_formatters
100response = make_request(method, params)
101File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
102packages\web3\middleware\gas_price_strategy.py", line 90, in 
103middleware
104return make_request(method, params)
105File "cytoolz/functoolz.pyx", line 250, in 
106cytoolz.functoolz.curry.__call__
107return self.func(*args, **kwargs)
108File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
109packages\web3\middleware\formatting.py", line 74, in 
110apply_formatters
111response = make_request(method, formatted_params)
112File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
113packages\web3\middleware\attrdict.py", line 33, in middleware
114response = make_request(method, params)
115File "cytoolz/functoolz.pyx", line 250, in 
116cytoolz.functoolz.curry.__call__
117return self.func(*args, **kwargs)
118File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
119packages\web3\middleware\formatting.py", line 74, in 
120apply_formatters
121response = make_request(method, formatted_params)
122File "cytoolz/functoolz.pyx", line 250, in 
123cytoolz.functoolz.curry.__call__
124return self.func(*args, **kwargs)
125File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
126packages\web3\middleware\formatting.py", line 73, in 
127apply_formatters
128formatted_params = formatter(params)
129File "cytoolz/functoolz.pyx", line 503, in 
130cytoolz.functoolz.Compose.__call__
131ret = PyObject_Call(self.first, args, kwargs)
132File "cytoolz/functoolz.pyx", line 250, in 
133cytoolz.functoolz.curry.__call__
134return self.func(*args, **kwargs)
135File "C:\Python310\lib\site-packages\eth_utils\decorators.py", line 
13691, in wrapper
137return ReturnType(result)  # type: ignore
138File "C:\Python310\lib\site-packages\eth_utils\applicators.py", line 
13922, in apply_formatter_at_index
140yield formatter(item)
141File "cytoolz/functoolz.pyx", line 250, in 
142cytoolz.functoolz.curry.__call__
143File "cytoolz/functoolz.pyx", line 250, in 
144cytoolz.functoolz.curry.__call__
145return self.func(*args, **kwargs)
146File "C:\Python310\lib\site-packages\eth_utils\applicators.py", line 
14772, in apply_formatter_if
148return formatter(value)
149File "cytoolz/functoolz.pyx", line 250, in 
150cytoolz.functoolz.curry.__call__
151return self.func(*args, **kwargs)
152File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
153packages\web3\middleware\validation.py", line 57, in 
154validate_chain_id
155raise ValidationError(
156web3.exceptions.ValidationError: The transaction declared chain ID 
1575777, but the connected node is on 1337
158

ANSWER

Answered 2022-Jan-17 at 18:17

Had this issue myself, apparently it's some sort of Ganache CLI error but the simplest fix I could find was to change the network id in Ganache through settings>server to 1337. It restarts the session so you'd then need to change the address and private key variable.

If it's the same tutorial I'm doing, you're likely to come unstuck after this... the code for transaction should be:

1from solcx import compile_standard
2from web3 import Web3
3import json
4import os
5from dotenv import load_dotenv
6
7load_dotenv()
8
9with open("./SimpleStorage.sol", "r") as file:
10    simple_storage_file = file.read()
11
12compiled_sol = compile_standard(
13    {
14        "language": "Solidity",
15        "sources": {"SimpleStorage.sol": {"content": simple_storage_file}},
16        "settings": {
17            "outputSelection": {
18                "*": {"*": ["abi", "metadata", "evm.bytecode", "evm.sourceMap"]}
19            }
20        },
21    },
22    solc_version="0.6.0",
23)
24
25with open("compiled_code.json", "w") as file:
26    json.dump(compiled_sol, file)
27
28
29# get bytecode
30bytecode = compiled_sol["contracts"]["SimpleStorage.sol"]["SimpleStorage"]["evm"][
31    "bytecode"
32]["object"]
33
34
35# get ABI
36abi = compiled_sol["contracts"]["SimpleStorage.sol"]["SimpleStorage"]["abi"]
37
38# to connect to ganache blockchain
39w3 = Web3(Web3.HTTPProvider("HTTP://127.0.0.1:7545"))
40chain_id = 5777
41my_address = "0xca1EA31e644F13E3E36631382686fD471c62267A"
42private_key = os.getenv("PRIVATE_KEY")
43
44
45# create the contract in python
46
47SimpleStorage = w3.eth.contract(abi=abi, bytecode=bytecode)
48
49# get the latest transaction
50nonce = w3.eth.getTransactionCount(my_address)
51
52# 1. Build a transaction
53# 2. Sign a transaction
54# 3. Send a transaction
55
56
57transaction = SimpleStorage.constructor().buildTransaction(
58    {"chainId": chain_id, "from": my_address, "nonce": nonce}
59)
60print(transaction)
61
62Traceback (most recent call last):
63File "C:\Users\evens\demos\web3_py_simple_storage\deploy.py", line 
6452, in <module>
65transaction = SimpleStorage.constructor().buildTransaction(
66File "C:\Python310\lib\site-packages\eth_utils\decorators.py", line 
6718, in _wrapper
68return self.method(obj, *args, **kwargs)
69File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
70packages\web3\contract.py", line 684, in buildTransaction
71return fill_transaction_defaults(self.web3, built_transaction)
72File "cytoolz/functoolz.pyx", line 250, in 
73cytoolz.functoolz.curry.__call__
74return self.func(*args, **kwargs)
75File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
76packages\web3\_utils\transactions.py", line 114, in 
77fill_transaction_defaults
78default_val = default_getter(web3, transaction)
79File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
80packages\web3\_utils\transactions.py", line 60, in <lambda>
81'gas': lambda web3, tx: web3.eth.estimate_gas(tx),
82File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
83packages\web3\eth.py", line 820, in estimate_gas
84return self._estimate_gas(transaction, block_identifier)
85File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
86packages\web3\module.py", line 57, in caller
87result = w3.manager.request_blocking(method_str,
88File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
89packages\web3\manager.py", line 197, in request_blocking
90response = self._make_request(method, params)
91File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
92packages\web3\manager.py", line 150, in _make_request
93return request_func(method, params)
94File "cytoolz/functoolz.pyx", line 250, in 
95cytoolz.functoolz.curry.__call__
96return self.func(*args, **kwargs)
97File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
98packages\web3\middleware\formatting.py", line 76, in 
99apply_formatters
100response = make_request(method, params)
101File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
102packages\web3\middleware\gas_price_strategy.py", line 90, in 
103middleware
104return make_request(method, params)
105File "cytoolz/functoolz.pyx", line 250, in 
106cytoolz.functoolz.curry.__call__
107return self.func(*args, **kwargs)
108File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
109packages\web3\middleware\formatting.py", line 74, in 
110apply_formatters
111response = make_request(method, formatted_params)
112File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
113packages\web3\middleware\attrdict.py", line 33, in middleware
114response = make_request(method, params)
115File "cytoolz/functoolz.pyx", line 250, in 
116cytoolz.functoolz.curry.__call__
117return self.func(*args, **kwargs)
118File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
119packages\web3\middleware\formatting.py", line 74, in 
120apply_formatters
121response = make_request(method, formatted_params)
122File "cytoolz/functoolz.pyx", line 250, in 
123cytoolz.functoolz.curry.__call__
124return self.func(*args, **kwargs)
125File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
126packages\web3\middleware\formatting.py", line 73, in 
127apply_formatters
128formatted_params = formatter(params)
129File "cytoolz/functoolz.pyx", line 503, in 
130cytoolz.functoolz.Compose.__call__
131ret = PyObject_Call(self.first, args, kwargs)
132File "cytoolz/functoolz.pyx", line 250, in 
133cytoolz.functoolz.curry.__call__
134return self.func(*args, **kwargs)
135File "C:\Python310\lib\site-packages\eth_utils\decorators.py", line 
13691, in wrapper
137return ReturnType(result)  # type: ignore
138File "C:\Python310\lib\site-packages\eth_utils\applicators.py", line 
13922, in apply_formatter_at_index
140yield formatter(item)
141File "cytoolz/functoolz.pyx", line 250, in 
142cytoolz.functoolz.curry.__call__
143File "cytoolz/functoolz.pyx", line 250, in 
144cytoolz.functoolz.curry.__call__
145return self.func(*args, **kwargs)
146File "C:\Python310\lib\site-packages\eth_utils\applicators.py", line 
14772, in apply_formatter_if
148return formatter(value)
149File "cytoolz/functoolz.pyx", line 250, in 
150cytoolz.functoolz.curry.__call__
151return self.func(*args, **kwargs)
152File "C:\Users\evens\AppData\Roaming\Python\Python310\site- 
153packages\web3\middleware\validation.py", line 57, in 
154validate_chain_id
155raise ValidationError(
156web3.exceptions.ValidationError: The transaction declared chain ID 
1575777, but the connected node is on 1337
158transaction = 
159 SimpleStorage.constructor().buildTransaction( {
160    "gasPrice": w3.eth.gas_price, 
161    "chainId": chain_id, 
162    "from": my_address, 
163    "nonce": nonce, 
164})
165print(transaction)
166

Otherwise you get a value error if you don't set the gasPrice

Source https://stackoverflow.com/questions/70731492

QUESTION

Lambda expressions and anonymous classes don't work when loaded as hidden classes

Asked 2022-Feb-26 at 05:14

I am trying to compile and load dynamically generated Java code during runtime. Since both ClassLoader::defineClass and Unsafe::defineAnonymousClass have serious drawbacks in this scenario, I tried using hidden classes via Lookup::defineHiddenClass instead. This works fine for all classes that I tried to load, except for those that call lambda expressions or contain anonymous classes.

Calling a lambda expression throws the following exception:

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8

Executing code that instantiates an anonymous class throws the following error:

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
9Exception Details:
10  Location:
11    tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400.run()V @5: invokespecial
12  Reason:
13    Type 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' (current frame, stack[2]) is not assignable to 'tests/HiddenClassLambdaTest$LambdaRunner'
14  Current Frame:
15    bci: @5
16    flags: { }
17    locals: { 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
18    stack: { uninitialized 0, uninitialized 0, 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
19  Bytecode:
20    0000000: bb00 1159 2ab7 0013 4cb1               
21
22    at java.base/java.lang.ClassLoader.defineClass0(Native Method)
23    at java.base/java.lang.System$2.defineClass(System.java:2193)
24    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2446)
25    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClassAsLookup(MethodHandles.java:2427)
26    at java.base/java.lang.invoke.MethodHandles$Lookup.defineHiddenClass(MethodHandles.java:2133)
27    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:25)
28
29

This is a short example that recreates the problem:

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
9Exception Details:
10  Location:
11    tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400.run()V @5: invokespecial
12  Reason:
13    Type 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' (current frame, stack[2]) is not assignable to 'tests/HiddenClassLambdaTest$LambdaRunner'
14  Current Frame:
15    bci: @5
16    flags: { }
17    locals: { 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
18    stack: { uninitialized 0, uninitialized 0, 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
19  Bytecode:
20    0000000: bb00 1159 2ab7 0013 4cb1               
21
22    at java.base/java.lang.ClassLoader.defineClass0(Native Method)
23    at java.base/java.lang.System$2.defineClass(System.java:2193)
24    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2446)
25    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClassAsLookup(MethodHandles.java:2427)
26    at java.base/java.lang.invoke.MethodHandles$Lookup.defineHiddenClass(MethodHandles.java:2133)
27    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:25)
28
29import java.lang.invoke.MethodHandles;
30
31public class HiddenClassLambdaTest {
32    /** This class is to be loaded and executed as hidden class */
33    public static final class LambdaRunner implements Runnable {
34        @Override public void run() {
35            Runnable runnable = () -> System.out.println("Success");
36            runnable.run();
37        }
38    }
39    
40    public static void main(String[] args) throws Throwable {
41        // Path to the class file of the nested class defined above
42        String nestedClassPath = HiddenClassLambdaTest.class.getTypeName().replace('.','/') + "$LambdaRunner.class";
43        // Class file content of the LambdaRunner class
44        byte[] classFileContents = HiddenClassLambdaTest.class.getClassLoader().getResourceAsStream(nestedClassPath).readAllBytes();
45        Class<?> lambdaRunnerClass = MethodHandles.lookup().defineHiddenClass(classFileContents, true).lookupClass();
46        Runnable lambdaRunnerInstance = (Runnable) lambdaRunnerClass.getConstructor().newInstance();
47        lambdaRunnerInstance.run();
48    }
49}
50

I've already tried compiling and running the code with different JDKs, using different ways to create new instances of the hidden class, searching for bugs at https://bugs.openjdk.java.net/, messing with the bytecode itself and several other things. I am not an expert on Java internals, so I am not sure whether I have not understood the JEP that introduced hidden classes correctly.

Am I doing something wrong, is this just impossible or is this a bug?

Edit: The JEP states

Migration should take the following into account: To invoke private nestmate instance methods from code in a hidden class, use invokevirtual or invokeinterface instead of invokespecial. Generated bytecode that uses invokespecial to invoke a private nestmate instance method will fail verification. invokespecial should only be used to invoke private nestmate constructors.

This might be the problem for the anonymous class. Is there a way to compile the code such that invokespecial is avoided in the bytecode?

ANSWER

Answered 2022-Feb-23 at 18:19

You can not turn arbitrary classes into hidden classes.

The documentation of defineHiddenClass contains the sentence

  • On any attempt to resolve the entry in the run-time constant pool indicated by this_class, the symbolic reference is considered to be resolved to C and resolution always succeeds immediately.

What it doesn’t spell out explicitly is that this is the only place where a type resolution ever ends up at the hidden class.

But it has been said unambiguously in bug report JDK-8222730:

For a hidden class, its specified hidden name should only be accessible through the hidden class's 'this_class' constant pool entry.

The class should not be accessible by specifying its original name in, for example, a method or field signature even within the hidden class.

Which we can check. Even a simple case like

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
9Exception Details:
10  Location:
11    tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400.run()V @5: invokespecial
12  Reason:
13    Type 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' (current frame, stack[2]) is not assignable to 'tests/HiddenClassLambdaTest$LambdaRunner'
14  Current Frame:
15    bci: @5
16    flags: { }
17    locals: { 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
18    stack: { uninitialized 0, uninitialized 0, 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
19  Bytecode:
20    0000000: bb00 1159 2ab7 0013 4cb1               
21
22    at java.base/java.lang.ClassLoader.defineClass0(Native Method)
23    at java.base/java.lang.System$2.defineClass(System.java:2193)
24    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2446)
25    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClassAsLookup(MethodHandles.java:2427)
26    at java.base/java.lang.invoke.MethodHandles$Lookup.defineHiddenClass(MethodHandles.java:2133)
27    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:25)
28
29import java.lang.invoke.MethodHandles;
30
31public class HiddenClassLambdaTest {
32    /** This class is to be loaded and executed as hidden class */
33    public static final class LambdaRunner implements Runnable {
34        @Override public void run() {
35            Runnable runnable = () -> System.out.println("Success");
36            runnable.run();
37        }
38    }
39    
40    public static void main(String[] args) throws Throwable {
41        // Path to the class file of the nested class defined above
42        String nestedClassPath = HiddenClassLambdaTest.class.getTypeName().replace('.','/') + "$LambdaRunner.class";
43        // Class file content of the LambdaRunner class
44        byte[] classFileContents = HiddenClassLambdaTest.class.getClassLoader().getResourceAsStream(nestedClassPath).readAllBytes();
45        Class<?> lambdaRunnerClass = MethodHandles.lookup().defineHiddenClass(classFileContents, true).lookupClass();
46        Runnable lambdaRunnerInstance = (Runnable) lambdaRunnerClass.getConstructor().newInstance();
47        lambdaRunnerInstance.run();
48    }
49}
50public class HiddenClassLambdaTest {
51
52    public static void main(String[] args) throws Throwable {
53        byte[] classFileContents = HiddenClassLambdaTest.class
54            .getResourceAsStream("HiddenClassLambdaTest$LambdaRunner.class")
55            .readAllBytes();
56        var hidden = MethodHandles.lookup()
57            .defineHiddenClass(classFileContents, true, ClassOption.NESTMATE);
58        Runnable lambdaRunnerInstance = (Runnable)hidden.findConstructor(
59            hidden.lookupClass(), MethodType.methodType(void.class)).invoke();
60        lambdaRunnerInstance.run();
61    }
62
63    static class LambdaRunner implements Runnable {
64        LambdaRunner field = this;
65
66        @Override
67        public void run() {
68        }
69    }
70}
71

will already fail. Note that it is a special case that the attempt to resolve the original class name LambdaRunner within the hidden class will not fail, as you used an existing class as template. So you get an IncompatibleClassChangeError or a VerifierError due to mismatches between the hidden class and the existing LambdaRunner class. When you don’t use a class definition of an existing class, you’d get a NoClassDefFoundError.

The same applies to

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
9Exception Details:
10  Location:
11    tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400.run()V @5: invokespecial
12  Reason:
13    Type 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' (current frame, stack[2]) is not assignable to 'tests/HiddenClassLambdaTest$LambdaRunner'
14  Current Frame:
15    bci: @5
16    flags: { }
17    locals: { 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
18    stack: { uninitialized 0, uninitialized 0, 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
19  Bytecode:
20    0000000: bb00 1159 2ab7 0013 4cb1               
21
22    at java.base/java.lang.ClassLoader.defineClass0(Native Method)
23    at java.base/java.lang.System$2.defineClass(System.java:2193)
24    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2446)
25    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClassAsLookup(MethodHandles.java:2427)
26    at java.base/java.lang.invoke.MethodHandles$Lookup.defineHiddenClass(MethodHandles.java:2133)
27    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:25)
28
29import java.lang.invoke.MethodHandles;
30
31public class HiddenClassLambdaTest {
32    /** This class is to be loaded and executed as hidden class */
33    public static final class LambdaRunner implements Runnable {
34        @Override public void run() {
35            Runnable runnable = () -> System.out.println("Success");
36            runnable.run();
37        }
38    }
39    
40    public static void main(String[] args) throws Throwable {
41        // Path to the class file of the nested class defined above
42        String nestedClassPath = HiddenClassLambdaTest.class.getTypeName().replace('.','/') + "$LambdaRunner.class";
43        // Class file content of the LambdaRunner class
44        byte[] classFileContents = HiddenClassLambdaTest.class.getClassLoader().getResourceAsStream(nestedClassPath).readAllBytes();
45        Class<?> lambdaRunnerClass = MethodHandles.lookup().defineHiddenClass(classFileContents, true).lookupClass();
46        Runnable lambdaRunnerInstance = (Runnable) lambdaRunnerClass.getConstructor().newInstance();
47        lambdaRunnerInstance.run();
48    }
49}
50public class HiddenClassLambdaTest {
51
52    public static void main(String[] args) throws Throwable {
53        byte[] classFileContents = HiddenClassLambdaTest.class
54            .getResourceAsStream("HiddenClassLambdaTest$LambdaRunner.class")
55            .readAllBytes();
56        var hidden = MethodHandles.lookup()
57            .defineHiddenClass(classFileContents, true, ClassOption.NESTMATE);
58        Runnable lambdaRunnerInstance = (Runnable)hidden.findConstructor(
59            hidden.lookupClass(), MethodType.methodType(void.class)).invoke();
60        lambdaRunnerInstance.run();
61    }
62
63    static class LambdaRunner implements Runnable {
64        LambdaRunner field = this;
65
66        @Override
67        public void run() {
68        }
69    }
70}
71    static class LambdaRunner implements Runnable {
72        static void method(LambdaRunner arg) {
73        }
74
75        @Override
76        public void run() {
77            method(this);
78        }
79    }
80

As the cited bug report said, neither field nor methods can refer to the hidden class in their signature.

A less intuitive example is

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
9Exception Details:
10  Location:
11    tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400.run()V @5: invokespecial
12  Reason:
13    Type 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' (current frame, stack[2]) is not assignable to 'tests/HiddenClassLambdaTest$LambdaRunner'
14  Current Frame:
15    bci: @5
16    flags: { }
17    locals: { 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
18    stack: { uninitialized 0, uninitialized 0, 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
19  Bytecode:
20    0000000: bb00 1159 2ab7 0013 4cb1               
21
22    at java.base/java.lang.ClassLoader.defineClass0(Native Method)
23    at java.base/java.lang.System$2.defineClass(System.java:2193)
24    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2446)
25    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClassAsLookup(MethodHandles.java:2427)
26    at java.base/java.lang.invoke.MethodHandles$Lookup.defineHiddenClass(MethodHandles.java:2133)
27    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:25)
28
29import java.lang.invoke.MethodHandles;
30
31public class HiddenClassLambdaTest {
32    /** This class is to be loaded and executed as hidden class */
33    public static final class LambdaRunner implements Runnable {
34        @Override public void run() {
35            Runnable runnable = () -> System.out.println("Success");
36            runnable.run();
37        }
38    }
39    
40    public static void main(String[] args) throws Throwable {
41        // Path to the class file of the nested class defined above
42        String nestedClassPath = HiddenClassLambdaTest.class.getTypeName().replace('.','/') + "$LambdaRunner.class";
43        // Class file content of the LambdaRunner class
44        byte[] classFileContents = HiddenClassLambdaTest.class.getClassLoader().getResourceAsStream(nestedClassPath).readAllBytes();
45        Class<?> lambdaRunnerClass = MethodHandles.lookup().defineHiddenClass(classFileContents, true).lookupClass();
46        Runnable lambdaRunnerInstance = (Runnable) lambdaRunnerClass.getConstructor().newInstance();
47        lambdaRunnerInstance.run();
48    }
49}
50public class HiddenClassLambdaTest {
51
52    public static void main(String[] args) throws Throwable {
53        byte[] classFileContents = HiddenClassLambdaTest.class
54            .getResourceAsStream("HiddenClassLambdaTest$LambdaRunner.class")
55            .readAllBytes();
56        var hidden = MethodHandles.lookup()
57            .defineHiddenClass(classFileContents, true, ClassOption.NESTMATE);
58        Runnable lambdaRunnerInstance = (Runnable)hidden.findConstructor(
59            hidden.lookupClass(), MethodType.methodType(void.class)).invoke();
60        lambdaRunnerInstance.run();
61    }
62
63    static class LambdaRunner implements Runnable {
64        LambdaRunner field = this;
65
66        @Override
67        public void run() {
68        }
69    }
70}
71    static class LambdaRunner implements Runnable {
72        static void method(LambdaRunner arg) {
73        }
74
75        @Override
76        public void run() {
77            method(this);
78        }
79    }
80    static class LambdaRunner implements Runnable {
81        @Override
82        public void run() {
83            System.out.println("" + this);
84        }
85    }
86

which will fail depending on the compiler and options, as when the StringConcatFactory is used, the behavior is like an invocation of a method having all non-constant parts as parameters and returning a String. So this is another case of having the hidden class in a method signature.


Lambda expressions are special, as a class like

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
9Exception Details:
10  Location:
11    tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400.run()V @5: invokespecial
12  Reason:
13    Type 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' (current frame, stack[2]) is not assignable to 'tests/HiddenClassLambdaTest$LambdaRunner'
14  Current Frame:
15    bci: @5
16    flags: { }
17    locals: { 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
18    stack: { uninitialized 0, uninitialized 0, 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
19  Bytecode:
20    0000000: bb00 1159 2ab7 0013 4cb1               
21
22    at java.base/java.lang.ClassLoader.defineClass0(Native Method)
23    at java.base/java.lang.System$2.defineClass(System.java:2193)
24    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2446)
25    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClassAsLookup(MethodHandles.java:2427)
26    at java.base/java.lang.invoke.MethodHandles$Lookup.defineHiddenClass(MethodHandles.java:2133)
27    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:25)
28
29import java.lang.invoke.MethodHandles;
30
31public class HiddenClassLambdaTest {
32    /** This class is to be loaded and executed as hidden class */
33    public static final class LambdaRunner implements Runnable {
34        @Override public void run() {
35            Runnable runnable = () -> System.out.println("Success");
36            runnable.run();
37        }
38    }
39    
40    public static void main(String[] args) throws Throwable {
41        // Path to the class file of the nested class defined above
42        String nestedClassPath = HiddenClassLambdaTest.class.getTypeName().replace('.','/') + "$LambdaRunner.class";
43        // Class file content of the LambdaRunner class
44        byte[] classFileContents = HiddenClassLambdaTest.class.getClassLoader().getResourceAsStream(nestedClassPath).readAllBytes();
45        Class<?> lambdaRunnerClass = MethodHandles.lookup().defineHiddenClass(classFileContents, true).lookupClass();
46        Runnable lambdaRunnerInstance = (Runnable) lambdaRunnerClass.getConstructor().newInstance();
47        lambdaRunnerInstance.run();
48    }
49}
50public class HiddenClassLambdaTest {
51
52    public static void main(String[] args) throws Throwable {
53        byte[] classFileContents = HiddenClassLambdaTest.class
54            .getResourceAsStream("HiddenClassLambdaTest$LambdaRunner.class")
55            .readAllBytes();
56        var hidden = MethodHandles.lookup()
57            .defineHiddenClass(classFileContents, true, ClassOption.NESTMATE);
58        Runnable lambdaRunnerInstance = (Runnable)hidden.findConstructor(
59            hidden.lookupClass(), MethodType.methodType(void.class)).invoke();
60        lambdaRunnerInstance.run();
61    }
62
63    static class LambdaRunner implements Runnable {
64        LambdaRunner field = this;
65
66        @Override
67        public void run() {
68        }
69    }
70}
71    static class LambdaRunner implements Runnable {
72        static void method(LambdaRunner arg) {
73        }
74
75        @Override
76        public void run() {
77            method(this);
78        }
79    }
80    static class LambdaRunner implements Runnable {
81        @Override
82        public void run() {
83            System.out.println("" + this);
84        }
85    }
86    static class LambdaRunner implements Runnable {
87        @Override
88        public void run() {
89            Runnable runnable = () -> System.out.println("Success");
90            runnable.run();
91        }
92    }
93

gets compiled similar to

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
9Exception Details:
10  Location:
11    tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400.run()V @5: invokespecial
12  Reason:
13    Type 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' (current frame, stack[2]) is not assignable to 'tests/HiddenClassLambdaTest$LambdaRunner'
14  Current Frame:
15    bci: @5
16    flags: { }
17    locals: { 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
18    stack: { uninitialized 0, uninitialized 0, 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
19  Bytecode:
20    0000000: bb00 1159 2ab7 0013 4cb1               
21
22    at java.base/java.lang.ClassLoader.defineClass0(Native Method)
23    at java.base/java.lang.System$2.defineClass(System.java:2193)
24    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2446)
25    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClassAsLookup(MethodHandles.java:2427)
26    at java.base/java.lang.invoke.MethodHandles$Lookup.defineHiddenClass(MethodHandles.java:2133)
27    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:25)
28
29import java.lang.invoke.MethodHandles;
30
31public class HiddenClassLambdaTest {
32    /** This class is to be loaded and executed as hidden class */
33    public static final class LambdaRunner implements Runnable {
34        @Override public void run() {
35            Runnable runnable = () -> System.out.println("Success");
36            runnable.run();
37        }
38    }
39    
40    public static void main(String[] args) throws Throwable {
41        // Path to the class file of the nested class defined above
42        String nestedClassPath = HiddenClassLambdaTest.class.getTypeName().replace('.','/') + "$LambdaRunner.class";
43        // Class file content of the LambdaRunner class
44        byte[] classFileContents = HiddenClassLambdaTest.class.getClassLoader().getResourceAsStream(nestedClassPath).readAllBytes();
45        Class<?> lambdaRunnerClass = MethodHandles.lookup().defineHiddenClass(classFileContents, true).lookupClass();
46        Runnable lambdaRunnerInstance = (Runnable) lambdaRunnerClass.getConstructor().newInstance();
47        lambdaRunnerInstance.run();
48    }
49}
50public class HiddenClassLambdaTest {
51
52    public static void main(String[] args) throws Throwable {
53        byte[] classFileContents = HiddenClassLambdaTest.class
54            .getResourceAsStream("HiddenClassLambdaTest$LambdaRunner.class")
55            .readAllBytes();
56        var hidden = MethodHandles.lookup()
57            .defineHiddenClass(classFileContents, true, ClassOption.NESTMATE);
58        Runnable lambdaRunnerInstance = (Runnable)hidden.findConstructor(
59            hidden.lookupClass(), MethodType.methodType(void.class)).invoke();
60        lambdaRunnerInstance.run();
61    }
62
63    static class LambdaRunner implements Runnable {
64        LambdaRunner field = this;
65
66        @Override
67        public void run() {
68        }
69    }
70}
71    static class LambdaRunner implements Runnable {
72        static void method(LambdaRunner arg) {
73        }
74
75        @Override
76        public void run() {
77            method(this);
78        }
79    }
80    static class LambdaRunner implements Runnable {
81        @Override
82        public void run() {
83            System.out.println("" + this);
84        }
85    }
86    static class LambdaRunner implements Runnable {
87        @Override
88        public void run() {
89            Runnable runnable = () -> System.out.println("Success");
90            runnable.run();
91        }
92    }
93    static class LambdaRunner implements Runnable {
94        @Override
95        public void run() {
96            Runnable runnable = LambdaRunner::lambdaBody;
97            runnable.run();
98        }
99        private static void lambdaBody() {
100            System.out.println("Success");
101        }
102    }
103

which doesn’t have the hidden class in the method signature, but has to refer to the method holding the body of the lambda expression as a MethodReference. Within the constant pool, the description of this method refers to its declaring class using the this_class entry. So it gets redirected to the hidden class as described in the documentation.

But the construction of the MethodType as part of the MethodReference does not use this information to load a Class like a class literal would do. Instead, it tries to load the hidden class through the defining class loader, which fails with the NoClassDefFoundError you have posted.

This seems to be related to JDK-8130087 which suggests that ordinary method resolution differs from the way, MethodType works, which can make MethodType fail where just invoking the method would work.

But it’s possible to demonstrate that even fixing this issue wouldn’t solve the general problem:

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
9Exception Details:
10  Location:
11    tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400.run()V @5: invokespecial
12  Reason:
13    Type 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' (current frame, stack[2]) is not assignable to 'tests/HiddenClassLambdaTest$LambdaRunner'
14  Current Frame:
15    bci: @5
16    flags: { }
17    locals: { 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
18    stack: { uninitialized 0, uninitialized 0, 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
19  Bytecode:
20    0000000: bb00 1159 2ab7 0013 4cb1               
21
22    at java.base/java.lang.ClassLoader.defineClass0(Native Method)
23    at java.base/java.lang.System$2.defineClass(System.java:2193)
24    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2446)
25    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClassAsLookup(MethodHandles.java:2427)
26    at java.base/java.lang.invoke.MethodHandles$Lookup.defineHiddenClass(MethodHandles.java:2133)
27    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:25)
28
29import java.lang.invoke.MethodHandles;
30
31public class HiddenClassLambdaTest {
32    /** This class is to be loaded and executed as hidden class */
33    public static final class LambdaRunner implements Runnable {
34        @Override public void run() {
35            Runnable runnable = () -> System.out.println("Success");
36            runnable.run();
37        }
38    }
39    
40    public static void main(String[] args) throws Throwable {
41        // Path to the class file of the nested class defined above
42        String nestedClassPath = HiddenClassLambdaTest.class.getTypeName().replace('.','/') + "$LambdaRunner.class";
43        // Class file content of the LambdaRunner class
44        byte[] classFileContents = HiddenClassLambdaTest.class.getClassLoader().getResourceAsStream(nestedClassPath).readAllBytes();
45        Class<?> lambdaRunnerClass = MethodHandles.lookup().defineHiddenClass(classFileContents, true).lookupClass();
46        Runnable lambdaRunnerInstance = (Runnable) lambdaRunnerClass.getConstructor().newInstance();
47        lambdaRunnerInstance.run();
48    }
49}
50public class HiddenClassLambdaTest {
51
52    public static void main(String[] args) throws Throwable {
53        byte[] classFileContents = HiddenClassLambdaTest.class
54            .getResourceAsStream("HiddenClassLambdaTest$LambdaRunner.class")
55            .readAllBytes();
56        var hidden = MethodHandles.lookup()
57            .defineHiddenClass(classFileContents, true, ClassOption.NESTMATE);
58        Runnable lambdaRunnerInstance = (Runnable)hidden.findConstructor(
59            hidden.lookupClass(), MethodType.methodType(void.class)).invoke();
60        lambdaRunnerInstance.run();
61    }
62
63    static class LambdaRunner implements Runnable {
64        LambdaRunner field = this;
65
66        @Override
67        public void run() {
68        }
69    }
70}
71    static class LambdaRunner implements Runnable {
72        static void method(LambdaRunner arg) {
73        }
74
75        @Override
76        public void run() {
77            method(this);
78        }
79    }
80    static class LambdaRunner implements Runnable {
81        @Override
82        public void run() {
83            System.out.println("" + this);
84        }
85    }
86    static class LambdaRunner implements Runnable {
87        @Override
88        public void run() {
89            Runnable runnable = () -> System.out.println("Success");
90            runnable.run();
91        }
92    }
93    static class LambdaRunner implements Runnable {
94        @Override
95        public void run() {
96            Runnable runnable = LambdaRunner::lambdaBody;
97            runnable.run();
98        }
99        private static void lambdaBody() {
100            System.out.println("Success");
101        }
102    }
103    static class LambdaRunner implements Runnable {
104        @Override
105        public void run() {
106            var lookup = MethodHandles.lookup();
107            var noArgVoid = MethodType.methodType(void.class);
108            try {
109                MethodHandle mh = LambdaMetafactory.metafactory(lookup, "run",
110                    MethodType.methodType(Runnable.class), noArgVoid,
111                    lookup.findStatic(LambdaRunner.class, "lambdaBody", noArgVoid),
112                    noArgVoid).getTarget();
113                System.out.println("got factory");
114                Runnable runnable = (Runnable)mh.invokeExact();
115                System.out.println("got runnable");
116                runnable.run();
117            }
118            catch(RuntimeException|Error e) {
119                throw e;
120            }
121            catch(Throwable e) {
122                throw new AssertionError(e);
123            }
124        }
125        private static void lambdaBody() {
126            System.out.println("Success");
127        }
128    }
129

This bypasses the problem described above and calls the LambdaMetafactory manually. When being redefined as hidden class, it will print:

1Exception in thread "main" java.lang.NoClassDefFoundError: tests/HiddenClassLambdaTest$LambdaRunner/0x0000000800c04400
2    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:22)
3Caused by: java.lang.ClassNotFoundException: tests.HiddenClassLambdaTest$LambdaRunner.0x0000000800c04400
4    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
5    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
6    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
7    ... 1 more
8Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
9Exception Details:
10  Location:
11    tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400.run()V @5: invokespecial
12  Reason:
13    Type 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' (current frame, stack[2]) is not assignable to 'tests/HiddenClassLambdaTest$LambdaRunner'
14  Current Frame:
15    bci: @5
16    flags: { }
17    locals: { 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
18    stack: { uninitialized 0, uninitialized 0, 'tests/HiddenClassLambdaTest$LambdaRunner+0x0000000800c00400' }
19  Bytecode:
20    0000000: bb00 1159 2ab7 0013 4cb1               
21
22    at java.base/java.lang.ClassLoader.defineClass0(Native Method)
23    at java.base/java.lang.System$2.defineClass(System.java:2193)
24    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClass(MethodHandles.java:2446)
25    at java.base/java.lang.invoke.MethodHandles$Lookup$ClassDefiner.defineClassAsLookup(MethodHandles.java:2427)
26    at java.base/java.lang.invoke.MethodHandles$Lookup.defineHiddenClass(MethodHandles.java:2133)
27    at tests.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:25)
28
29import java.lang.invoke.MethodHandles;
30
31public class HiddenClassLambdaTest {
32    /** This class is to be loaded and executed as hidden class */
33    public static final class LambdaRunner implements Runnable {
34        @Override public void run() {
35            Runnable runnable = () -> System.out.println("Success");
36            runnable.run();
37        }
38    }
39    
40    public static void main(String[] args) throws Throwable {
41        // Path to the class file of the nested class defined above
42        String nestedClassPath = HiddenClassLambdaTest.class.getTypeName().replace('.','/') + "$LambdaRunner.class";
43        // Class file content of the LambdaRunner class
44        byte[] classFileContents = HiddenClassLambdaTest.class.getClassLoader().getResourceAsStream(nestedClassPath).readAllBytes();
45        Class<?> lambdaRunnerClass = MethodHandles.lookup().defineHiddenClass(classFileContents, true).lookupClass();
46        Runnable lambdaRunnerInstance = (Runnable) lambdaRunnerClass.getConstructor().newInstance();
47        lambdaRunnerInstance.run();
48    }
49}
50public class HiddenClassLambdaTest {
51
52    public static void main(String[] args) throws Throwable {
53        byte[] classFileContents = HiddenClassLambdaTest.class
54            .getResourceAsStream("HiddenClassLambdaTest$LambdaRunner.class")
55            .readAllBytes();
56        var hidden = MethodHandles.lookup()
57            .defineHiddenClass(classFileContents, true, ClassOption.NESTMATE);
58        Runnable lambdaRunnerInstance = (Runnable)hidden.findConstructor(
59            hidden.lookupClass(), MethodType.methodType(void.class)).invoke();
60        lambdaRunnerInstance.run();
61    }
62
63    static class LambdaRunner implements Runnable {
64        LambdaRunner field = this;
65
66        @Override
67        public void run() {
68        }
69    }
70}
71    static class LambdaRunner implements Runnable {
72        static void method(LambdaRunner arg) {
73        }
74
75        @Override
76        public void run() {
77            method(this);
78        }
79    }
80    static class LambdaRunner implements Runnable {
81        @Override
82        public void run() {
83            System.out.println("" + this);
84        }
85    }
86    static class LambdaRunner implements Runnable {
87        @Override
88        public void run() {
89            Runnable runnable = () -> System.out.println("Success");
90            runnable.run();
91        }
92    }
93    static class LambdaRunner implements Runnable {
94        @Override
95        public void run() {
96            Runnable runnable = LambdaRunner::lambdaBody;
97            runnable.run();
98        }
99        private static void lambdaBody() {
100            System.out.println("Success");
101        }
102    }
103    static class LambdaRunner implements Runnable {
104        @Override
105        public void run() {
106            var lookup = MethodHandles.lookup();
107            var noArgVoid = MethodType.methodType(void.class);
108            try {
109                MethodHandle mh = LambdaMetafactory.metafactory(lookup, "run",
110                    MethodType.methodType(Runnable.class), noArgVoid,
111                    lookup.findStatic(LambdaRunner.class, "lambdaBody", noArgVoid),
112                    noArgVoid).getTarget();
113                System.out.println("got factory");
114                Runnable runnable = (Runnable)mh.invokeExact();
115                System.out.println("got runnable");
116                runnable.run();
117            }
118            catch(RuntimeException|Error e) {
119                throw e;
120            }
121            catch(Throwable e) {
122                throw new AssertionError(e);
123            }
124        }
125        private static void lambdaBody() {
126            System.out.println("Success");
127        }
128    }
129got factory
130got runnable
131Exception in thread "main" java.lang.NoClassDefFoundError: test/HiddenClassLambdaTest$LambdaRunner/0x0000000800c01400
132    at test/test.HiddenClassLambdaTest.main(HiddenClassLambdaTest.java:15)
133Caused by: java.lang.ClassNotFoundException: test.HiddenClassLambdaTest$LambdaRunner.0x0000000800c01400
134    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
135    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
136    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
137    ... 1 more
138

which shows that all obstacles have been circumvented, but when it comes to the actual invocation from the generated Runnable to the method holding the lambda body, it will fail due to the fact that the target class is hidden. A JVM with eager resolution of symbolic references might fail earlier, i.e. the example might not print got runnable then.

Unlike the old JVM anonymous classes, there is no way to link to a hidden class, not even from another hidden class.


The bottom line is, as said at the beginning, you can not turn arbitrary classes into hidden classes. Lambda expressions are not the only feature not working with hidden classes. It’s not a good idea to try and get surprised. Hidden classes should only be used in conjunction with bytecode generators carefully using only features known to work.

Source https://stackoverflow.com/questions/71224833

QUESTION

How is CPython implemented?

Asked 2022-Feb-10 at 02:37

So I lately came across an explanation for Python's interpreter and compiler (CPython specifically).

Please correct me if I'm wrong. I just want to be sure I understand these specific concepts.

So CPython gets both compiled (to bytecode) and then interpreted (in the PVM)? And what does the PVM do exactly? Does it read the bytecode line by line, and translate each one to binary instructions that can be executed on a specific computer? Does this mean that a computer based on an Intel processor needs a different PVM from an AMD-based computer?

ANSWER

Answered 2022-Feb-09 at 13:49
  1. Yes, CPython is compiled to bytecode which is then executed by the virtual machine.
  2. The virtual machine executes instructions one-by-one. It's written in C (but you can write it in another language) and looks like a huge if/else statement like "if the current instruction is this, do this; if the instruction is this, do another thing", and so on. Instructions aren't translated to binary - that's why it's called an interpreter.
    1. You can find the list of instructions here: https://docs.python.org/3.10/library/dis.html#python-bytecode-instructions
    2. The implementation of the VM is available here: https://github.com/python/cpython/blob/f71a69aa9209cf67cc1060051b147d6afa379bba/Python/ceval.c#L1718
  3. Bytecode doesn't have a concept of "line": it's just a stream of bytes. The interpreter can read one byte at a time and use another if/else statement to decide what instruction it's looking at. For example:
1curr_byte = read_byte()
2if curr_byte == 0x00:
3   # Parse instruction with no arguments
4   curr_instruction = DO_THING_A;
5   args = NULL;
6elif curr_byte == 0x01:
7   another_byte = read_byte()
8   if another_byte == 0x00:
9      # Parse a two-byte instruction
10      curr_instruction = DO_THING_B;
11      args = NULL;
12   else:
13      # Parse a one-byte instruction
14      # with one argument
15      curr_instruction = DO_THING_C;
16      args = another_byte >> 1; # or whatever
17elif curr_byte == ...:
18   ... # go on and on and on
19
  • The entire point of bytecode is that it can be executed by another program (the interpreter, or virtual machine) on almost any hardware. For example, in order to get CPython running on new hardware, you'll need a C toolchain (compiler, linker, assembler etc) for this hardware and a bunch of functions that Python can call to do low-level stuff (allocate memory, output text, do networking etc). Once you have that, write C code that can execute the bytecode - and that's it.
  • Source https://stackoverflow.com/questions/71050098

    QUESTION

    Bad request when deploying smart contract

    Asked 2022-Jan-18 at 21:38

    So I'm currently trying to deploy a router smart contract. I've been building it through erdpy contract build, which has been successful (I'm on rust nightly tool chain as the Smart contract needs it). And I am now trying to deploy it, but I can't manage to do it. I keep having a 400 BadRequest from https://devnet-api.elrond.com/transaction/send.

    Here are the logs from the deployment:

    1erdpy contract deploy
    2INFO:accounts:Account.sync_nonce()
    3INFO:accounts:Account.sync_nonce() done: 0
    4INFO:cli.contracts:Contract address: erd1qqqqqqqqqqqqqpgqzqv7kk893c3ftwgaekvvv9whpqcfn4kazqxq3mud36
    5INFO:transactions:Transaction.send: nonce=0
    6CRITICAL:cli:Proxy request error for url [https://devnet-api.elrond.com/transaction/send]: {'statusCode': 400, 'message': 'Bad Request'}
    7
    8

    And here is erdpy.json used to configure the command:

    1erdpy contract deploy
    2INFO:accounts:Account.sync_nonce()
    3INFO:accounts:Account.sync_nonce() done: 0
    4INFO:cli.contracts:Contract address: erd1qqqqqqqqqqqqqpgqzqv7kk893c3ftwgaekvvv9whpqcfn4kazqxq3mud36
    5INFO:transactions:Transaction.send: nonce=0
    6CRITICAL:cli:Proxy request error for url [https://devnet-api.elrond.com/transaction/send]: {'statusCode': 400, 'message': 'Bad Request'}
    7
    8{
    9    "configurations": {
    10        "default": {
    11            "proxy": "https://devnet-api.elrond.com",
    12            "chainID": "D"
    13        }
    14    },
    15    "contract":{
    16        "deploy":{
    17            "verbose": true,
    18            "bytecode": "output/router.wasm",
    19            "recall-nonce": true,
    20            "nonce": 1,
    21            "pem": "../../../wallets/owner/wallet-owner.pem",
    22            "gas-limit": 600000000,
    23            "send": true,
    24            "outfile": "deploy-testnet.interaction.json"
    25        }
    26    }
    27}
    28
    29

    The contract I'm trying to deploy is the following. I've also been through the OpenAPI Spec or the documentation searching for an answer, but there is nothing about it. This route is normally returning error message, but for this specific case it is not.

    Some other contract like ping-pong are working properly with the same erdpy.json config.

    ANSWER

    Answered 2022-Jan-05 at 10:47

    I have you tried to deploy with the argument --verbose?

    That should be something like that (not sure of the syntax because I am on phone) erdpy --verbose contract deploy

    Source https://stackoverflow.com/questions/70550705

    QUESTION

    JavaScript: V8 question: are small integers pooled?

    Asked 2022-Jan-17 at 12:37

    was looking at this V8 design doc where it has a section for Constant Pool Entries

    it says

    Constant pools are used to store heap objects and small integers that are referenced as constants in generated bytecode. and

    ... Small integers and the strong referenced oddball type’s have bytecodes to load them directly and do not go into the constant pool.

    So I am confused: are small integers pooled or not?

    My understanding is that it is not worth it pooling small integers if sizeof(int) < sizeof(int *) - because it is cheaper to just copy the actual integer instead of copying the pointer that points to the integer in the constant pool. Also variables that hold integers can be optimised to be stored directly in CPU registers and skip being allocated in memory first.

    Also, are they located on the V8 heap or the stack? My understanding had always been that smis are just be the immediate values allocated on the stack instead of being a pointer + an integer allocated on heap. Also if you take a heap snapshot using chrome devtool you cannot find smis in the heap snapshot - only heap number such as big integers or double like 3.14 are on the heap until I saw this article https://v8.dev/blog/pointer-compression#value-tagging-in-v8

    JavaScript values in V8 are represented as objects and allocated on the V8 heap, no matter if they are objects, arrays, numbers or strings. This allows us to represent any value as a pointer to an object.

    Now I am just baffled - are smis also allocated on the heap?

    ANSWER

    Answered 2022-Jan-17 at 12:37

    V8 developer here.

    are small integers pooled or not?

    They are not (at least not right now). That said, this is a small implementation detail and could be done either way: it would totally be possible to use the constant pool for Smis. I suppose the decision to build special machinery for Smis (instead of reusing the general-purpose constant pool) was made because things turned out to be more efficient that way.

    it is not worth it pooling small integers if sizeof(int) < sizeof(int *)

    The details are different (a Smi is not an int, and constant pool slots are referenced by index rather than C++ pointer), but this reasoning does go in the right direction: avoiding indirections can save time and memory.

    are smis also allocated on the heap?

    Yes, everything is allocated on the heap. The stack is only useful for temporary (and sufficiently small) things; that's largely unrelated to the type of thing.

    The "trick" of Smis is that they're not stored as separate objects: when you have an object that refers to a Smi, such as let foo = {smi: 42}, then the value 42 can be smi-encoded and stored directly inside the "foo" object (whereas if the value was 42.5, then the object would store a pointer to a separate "HeapNumber"). But since the object is on the heap, so is the Smi.

    @DanielCruz

    What I understand [...] is that constant small integers are pooled. Variable small integers are not.

    Nope. Any literal that occurs in source code is "constant". Whether you use let or const for your variables has nothing to do with this.

    Source https://stackoverflow.com/questions/70734678

    QUESTION

    env_parent(): different results when using default argument or when passing explicitly default argument

    Asked 2022-Jan-15 at 21:30

    I have noticed different behavior when using env_parent() from rlang package and when using env_parent(caller_env()), although caller_env() is a default argument for env_parent() first parameter:

    1library(rlang)
    2env_parent
    3#&gt; function (env = caller_env(), n = 1) 
    4#&gt; {
    5#&gt;     env_ &lt;- get_env_retired(env, &quot;env_parent()&quot;)
    6#&gt;     while (n &gt; 0) {
    7#&gt;         if (is_empty_env(env_)) {
    8#&gt;             abort(&quot;The empty environment has no parent&quot;)
    9#&gt;         }
    10#&gt;         n &lt;- n - 1
    11#&gt;         env_ &lt;- parent.env(env_)
    12#&gt;     }
    13#&gt;     env_
    14#&gt; }
    15#&gt; &lt;bytecode: 0x000000001d8ad000&gt;
    16#&gt; &lt;environment: namespace:rlang&gt;
    17

    I'm not very familiar with environments and I was able to prepare MRE only based on shiny app (I have noticed this using shiny app). It is important to have app in two files - ui.R and server.R:

    ui.R

    1library(rlang)
    2env_parent
    3#&gt; function (env = caller_env(), n = 1) 
    4#&gt; {
    5#&gt;     env_ &lt;- get_env_retired(env, &quot;env_parent()&quot;)
    6#&gt;     while (n &gt; 0) {
    7#&gt;         if (is_empty_env(env_)) {
    8#&gt;             abort(&quot;The empty environment has no parent&quot;)
    9#&gt;         }
    10#&gt;         n &lt;- n - 1
    11#&gt;         env_ &lt;- parent.env(env_)
    12#&gt;     }
    13#&gt;     env_
    14#&gt; }
    15#&gt; &lt;bytecode: 0x000000001d8ad000&gt;
    16#&gt; &lt;environment: namespace:rlang&gt;
    17library(shiny)
    18library(rlang)
    19
    20parent &lt;&lt;- function() {
    21  env_parent()
    22}
    23
    24parents_default_arg_passed &lt;&lt;- function() {
    25  env_parent(caller_env())
    26}
    27
    28ui &lt;- fluidPage(
    29  textOutput(&quot;env_parent&quot;),
    30  textOutput(&quot;env_parents_default_arg_passed&quot;)
    31)
    32

    server.R

    1library(rlang)
    2env_parent
    3#&gt; function (env = caller_env(), n = 1) 
    4#&gt; {
    5#&gt;     env_ &lt;- get_env_retired(env, &quot;env_parent()&quot;)
    6#&gt;     while (n &gt; 0) {
    7#&gt;         if (is_empty_env(env_)) {
    8#&gt;             abort(&quot;The empty environment has no parent&quot;)
    9#&gt;         }
    10#&gt;         n &lt;- n - 1
    11#&gt;         env_ &lt;- parent.env(env_)
    12#&gt;     }
    13#&gt;     env_
    14#&gt; }
    15#&gt; &lt;bytecode: 0x000000001d8ad000&gt;
    16#&gt; &lt;environment: namespace:rlang&gt;
    17library(shiny)
    18library(rlang)
    19
    20parent &lt;&lt;- function() {
    21  env_parent()
    22}
    23
    24parents_default_arg_passed &lt;&lt;- function() {
    25  env_parent(caller_env())
    26}
    27
    28ui &lt;- fluidPage(
    29  textOutput(&quot;env_parent&quot;),
    30  textOutput(&quot;env_parents_default_arg_passed&quot;)
    31)
    32server &lt;- function(input, output, session) {
    33  
    34  output$env_parent &lt;- renderPrint({
    35    names(parent())
    36  })
    37  
    38  output$env_parents_default_arg_passed &lt;- renderPrint({
    39    names(parents_default_arg_passed())
    40  })
    41  
    42}
    43

    I see this output after running the app:

    1library(rlang)
    2env_parent
    3#&gt; function (env = caller_env(), n = 1) 
    4#&gt; {
    5#&gt;     env_ &lt;- get_env_retired(env, &quot;env_parent()&quot;)
    6#&gt;     while (n &gt; 0) {
    7#&gt;         if (is_empty_env(env_)) {
    8#&gt;             abort(&quot;The empty environment has no parent&quot;)
    9#&gt;         }
    10#&gt;         n &lt;- n - 1
    11#&gt;         env_ &lt;- parent.env(env_)
    12#&gt;     }
    13#&gt;     env_
    14#&gt; }
    15#&gt; &lt;bytecode: 0x000000001d8ad000&gt;
    16#&gt; &lt;environment: namespace:rlang&gt;
    17library(shiny)
    18library(rlang)
    19
    20parent &lt;&lt;- function() {
    21  env_parent()
    22}
    23
    24parents_default_arg_passed &lt;&lt;- function() {
    25  env_parent(caller_env())
    26}
    27
    28ui &lt;- fluidPage(
    29  textOutput(&quot;env_parent&quot;),
    30  textOutput(&quot;env_parents_default_arg_passed&quot;)
    31)
    32server &lt;- function(input, output, session) {
    33  
    34  output$env_parent &lt;- renderPrint({
    35    names(parent())
    36  })
    37  
    38  output$env_parents_default_arg_passed &lt;- renderPrint({
    39    names(parents_default_arg_passed())
    40  })
    41  
    42}
    43[1] &quot;ui&quot;
    44[1] &quot;~&quot; &quot;.__tidyeval_quosure_mask__.&quot;
    45

    Why is that?

    ANSWER

    Answered 2022-Jan-15 at 21:30

    The short answer to your question is, there is a difference between explicitly calling a function with an argument, compared to calling the function and letting it supply the same argument as default by itself. In the latter case, the caller environment is the execution environment of the function. In the former case the caller environment is where the function was explicitly called from.

    It took me a while to find a nice visualization of what is going on, but I think I found one.

    Let's create two functions similar to {rlang}'s env_parent and caller_env. The difference is that myCallEnv will not only return the execution environment of the calling function, it will also show the call strack tree with lobstr::cst():

    1library(rlang)
    2env_parent
    3#&gt; function (env = caller_env(), n = 1) 
    4#&gt; {
    5#&gt;     env_ &lt;- get_env_retired(env, &quot;env_parent()&quot;)
    6#&gt;     while (n &gt; 0) {
    7#&gt;         if (is_empty_env(env_)) {
    8#&gt;             abort(&quot;The empty environment has no parent&quot;)
    9#&gt;         }
    10#&gt;         n &lt;- n - 1
    11#&gt;         env_ &lt;- parent.env(env_)
    12#&gt;     }
    13#&gt;     env_
    14#&gt; }
    15#&gt; &lt;bytecode: 0x000000001d8ad000&gt;
    16#&gt; &lt;environment: namespace:rlang&gt;
    17library(shiny)
    18library(rlang)
    19
    20parent &lt;&lt;- function() {
    21  env_parent()
    22}
    23
    24parents_default_arg_passed &lt;&lt;- function() {
    25  env_parent(caller_env())
    26}
    27
    28ui &lt;- fluidPage(
    29  textOutput(&quot;env_parent&quot;),
    30  textOutput(&quot;env_parents_default_arg_passed&quot;)
    31)
    32server &lt;- function(input, output, session) {
    33  
    34  output$env_parent &lt;- renderPrint({
    35    names(parent())
    36  })
    37  
    38  output$env_parents_default_arg_passed &lt;- renderPrint({
    39    names(parents_default_arg_passed())
    40  })
    41  
    42}
    43[1] &quot;ui&quot;
    44[1] &quot;~&quot; &quot;.__tidyeval_quosure_mask__.&quot;
    45myCallEnv &lt;- function() {
    46    print(lobstr::cst())
    47    caller_env(n = 1)
    48  }
    49
    50myEnvParent &lt;- function(e = myCallEnv()) {
    51  env_parent(env = e)
    52}
    53

    Now let's call myEnvParent one time with its default argument and one time by supplying the same default argument explicitly:

    1library(rlang)
    2env_parent
    3#&gt; function (env = caller_env(), n = 1) 
    4#&gt; {
    5#&gt;     env_ &lt;- get_env_retired(env, &quot;env_parent()&quot;)
    6#&gt;     while (n &gt; 0) {
    7#&gt;         if (is_empty_env(env_)) {
    8#&gt;             abort(&quot;The empty environment has no parent&quot;)
    9#&gt;         }
    10#&gt;         n &lt;- n - 1
    11#&gt;         env_ &lt;- parent.env(env_)
    12#&gt;     }
    13#&gt;     env_
    14#&gt; }
    15#&gt; &lt;bytecode: 0x000000001d8ad000&gt;
    16#&gt; &lt;environment: namespace:rlang&gt;
    17library(shiny)
    18library(rlang)
    19
    20parent &lt;&lt;- function() {
    21  env_parent()
    22}
    23
    24parents_default_arg_passed &lt;&lt;- function() {
    25  env_parent(caller_env())
    26}
    27
    28ui &lt;- fluidPage(
    29  textOutput(&quot;env_parent&quot;),
    30  textOutput(&quot;env_parents_default_arg_passed&quot;)
    31)
    32server &lt;- function(input, output, session) {
    33  
    34  output$env_parent &lt;- renderPrint({
    35    names(parent())
    36  })
    37  
    38  output$env_parents_default_arg_passed &lt;- renderPrint({
    39    names(parents_default_arg_passed())
    40  })
    41  
    42}
    43[1] &quot;ui&quot;
    44[1] &quot;~&quot; &quot;.__tidyeval_quosure_mask__.&quot;
    45myCallEnv &lt;- function() {
    46    print(lobstr::cst())
    47    caller_env(n = 1)
    48  }
    49
    50myEnvParent &lt;- function(e = myCallEnv()) {
    51  env_parent(env = e)
    52}
    53myEnvParent()
    54#    ▆
    55# 1. └─global myEnvParent()
    56# 2.   ├─rlang::env_parent(env = e)
    57# 3.   │ └─rlang:::get_env_retired(env, &quot;env_parent()&quot;)
    58# 4.   │   └─rlang::is_environment(x)
    59# 5.   └─global myCallEnv()
    60# 6.     ├─base::print(lobstr::cst())
    61# 7.     └─lobstr::cst()
    62# NULL
    63# &lt;environment: R_GlobalEnv&gt;
    64
    65myEnvParent(myCallEnv())
    66#    ▆
    67# 1. ├─global myEnvParent(myCallEnv())
    68# 2. │ └─rlang::env_parent(env = e)
    69# 3. │   └─rlang:::get_env_retired(env, &quot;env_parent()&quot;)
    70# 4. │     └─rlang::is_environment(x)
    71# 5. └─global myCallEnv()
    72# 6.   ├─base::print(lobstr::cst())
    73# 7.   └─lobstr::cst()
    74# NULL
    75# &lt;environment: package:rlang&gt;
    76# attr(,&quot;name&quot;)
    77# [1] &quot;package:rlang&quot;
    78# attr(,&quot;path&quot;)
    79# [1] # &quot;/Library/Frameworks/R.framework/Versions/4.0/Resources/library/rlang&quot;
    80

    Comparing both outputs we can see that in the first call, myEnvParent(), myCallEnv() is called from the execution environment of myEnvParent(). The parent environment is the global environment R_GlobalEnv.

    In the second call, myEnvParent(myCallEnv()), myCallEnv() is called from the global environment and therefore its parent is the second environment on the search path:

    1library(rlang)
    2env_parent
    3#&gt; function (env = caller_env(), n = 1) 
    4#&gt; {
    5#&gt;     env_ &lt;- get_env_retired(env, &quot;env_parent()&quot;)
    6#&gt;     while (n &gt; 0) {
    7#&gt;         if (is_empty_env(env_)) {
    8#&gt;             abort(&quot;The empty environment has no parent&quot;)
    9#&gt;         }
    10#&gt;         n &lt;- n - 1
    11#&gt;         env_ &lt;- parent.env(env_)
    12#&gt;     }
    13#&gt;     env_
    14#&gt; }
    15#&gt; &lt;bytecode: 0x000000001d8ad000&gt;
    16#&gt; &lt;environment: namespace:rlang&gt;
    17library(shiny)
    18library(rlang)
    19
    20parent &lt;&lt;- function() {
    21  env_parent()
    22}
    23
    24parents_default_arg_passed &lt;&lt;- function() {
    25  env_parent(caller_env())
    26}
    27
    28ui &lt;- fluidPage(
    29  textOutput(&quot;env_parent&quot;),
    30  textOutput(&quot;env_parents_default_arg_passed&quot;)
    31)
    32server &lt;- function(input, output, session) {
    33  
    34  output$env_parent &lt;- renderPrint({
    35    names(parent())
    36  })
    37  
    38  output$env_parents_default_arg_passed &lt;- renderPrint({
    39    names(parents_default_arg_passed())
    40  })
    41  
    42}
    43[1] &quot;ui&quot;
    44[1] &quot;~&quot; &quot;.__tidyeval_quosure_mask__.&quot;
    45myCallEnv &lt;- function() {
    46    print(lobstr::cst())
    47    caller_env(n = 1)
    48  }
    49
    50myEnvParent &lt;- function(e = myCallEnv()) {
    51  env_parent(env = e)
    52}
    53myEnvParent()
    54#    ▆
    55# 1. └─global myEnvParent()
    56# 2.   ├─rlang::env_parent(env = e)
    57# 3.   │ └─rlang:::get_env_retired(env, &quot;env_parent()&quot;)
    58# 4.   │   └─rlang::is_environment(x)
    59# 5.   └─global myCallEnv()
    60# 6.     ├─base::print(lobstr::cst())
    61# 7.     └─lobstr::cst()
    62# NULL
    63# &lt;environment: R_GlobalEnv&gt;
    64
    65myEnvParent(myCallEnv())
    66#    ▆
    67# 1. ├─global myEnvParent(myCallEnv())
    68# 2. │ └─rlang::env_parent(env = e)
    69# 3. │   └─rlang:::get_env_retired(env, &quot;env_parent()&quot;)
    70# 4. │     └─rlang::is_environment(x)
    71# 5. └─global myCallEnv()
    72# 6.   ├─base::print(lobstr::cst())
    73# 7.   └─lobstr::cst()
    74# NULL
    75# &lt;environment: package:rlang&gt;
    76# attr(,&quot;name&quot;)
    77# [1] &quot;package:rlang&quot;
    78# attr(,&quot;path&quot;)
    79# [1] # &quot;/Library/Frameworks/R.framework/Versions/4.0/Resources/library/rlang&quot;
    80searchpaths()
    81# [1] &quot;.GlobalEnv&quot;                                                              
    82# [2] &quot;/Library/Frameworks/R.framework/Versions/4.0/Resources/library/rlang&quot;    
    83# [3] &quot;tools:rstudio&quot;                                                           
    84# [4] &quot;/Library/Frameworks/R.framework/Versions/4.0/Resources/library/stats&quot;    
    85# [5] &quot;/Library/Frameworks/R.framework/Versions/4.0/Resources/library/graphics&quot; 
    86# [6] &quot;/Library/Frameworks/R.framework/Versions/4.0/Resources/library/grDevices&quot;
    87# [7] &quot;/Library/Frameworks/R.framework/Versions/4.0/Resources/library/utils&quot;    
    88# [8] &quot;/Library/Frameworks/R.framework/Versions/4.0/Resources/library/datasets&quot; 
    89# [9] &quot;/Library/Frameworks/R.framework/Versions/4.0/Resources/library/methods&quot;  
    90#[10] &quot;Autoloads&quot;                                                               
    91#[11] &quot;/Library/Frameworks/R.framework/Resources/library/base&quot;   
    92

    Source https://stackoverflow.com/questions/70626136

    QUESTION

    looping over array, performance difference between indexed and enhanced for loop

    Asked 2022-Jan-05 at 19:41

    The JLS states, that for arrays, "The enhanced for statement is equivalent to a basic for statement of the form". However if I check the generated bytecode for JDK8, for both variants different bytecode is generated, and if I try to measure the performance, surprisingly, the enhanced one seems to be giving better results(on jdk8)... Can someone advise why it's that? I'd guess it's because of incorrect jmh testing, so if it's that, please suggest how to fix that. (I know that JMH states not to test using loops, but I don't think this applies here, as I'm actually trying to measure the loops here)

    My JMH testing was rather simple (probably too simple), but I cannot explain the results. Testing JMH code is below, typical results are:

    1JdkBenchmarks.enhanced  avgt    5  2556.281 ±  31.789  ns/op
    2JdkBenchmarks.indexed   avgt    5  4032.164 ± 100.121  ns/op
    3

    meaning typically enhanced for loop is faster, and measurement for it is more accurate than for indexed loop, so we cannot address the difference to measurement uncertainty. Principally the same results are for array initialized with random integers, or bigger arrays.

    1JdkBenchmarks.enhanced  avgt    5  2556.281 ±  31.789  ns/op
    2JdkBenchmarks.indexed   avgt    5  4032.164 ± 100.121  ns/op
    3public class JdkBenchmarks {
    4
    5    @Benchmark
    6    @BenchmarkMode(AverageTime)
    7    @OutputTimeUnit(NANOSECONDS)
    8    public void indexed(Blackhole blackhole, TestState testState) {
    9        int length = testState.values.length;
    10        for(int i = 0; i &lt; length; i++) {
    11            blackhole.consume(testState.values[i]);
    12        }
    13    }
    14
    15    @Benchmark
    16    @BenchmarkMode(AverageTime)
    17    @OutputTimeUnit(NANOSECONDS)
    18    public void enhanced(Blackhole blackhole, TestState testState) {
    19        for (int value : testState.values) {
    20            blackhole.consume(value);
    21        }
    22    }
    23
    24
    25    @State(Scope.Benchmark)
    26    public static class TestState {
    27        public int[] values;
    28
    29        @Setup
    30        public void setupArray() {
    31            int count = 1000;
    32            values = new int[count];
    33            for(int i = 0; i &lt; count; i++) {
    34                values[i] = i;
    35            }
    36        }
    37    }
    38
    39    public static void main(String[] args) throws RunnerException {
    40        Options opt = new OptionsBuilder()
    41                .include(JdkBenchmarks.class.getSimpleName())
    42                .forks(1)
    43                .build();
    44
    45        new Runner(opt).run();
    46    }
    47
    48}
    49

    ANSWER

    Answered 2022-Jan-05 at 19:41

    TL;DR: You are observing what happens when JIT compiler cannot trust that values are not changing inside the loop. Additionally, in the tiny benchmark like this, Blackhole.consume costs dominate, obscuring the results.

    Simplifying the test:

    1JdkBenchmarks.enhanced  avgt    5  2556.281 ±  31.789  ns/op
    2JdkBenchmarks.indexed   avgt    5  4032.164 ± 100.121  ns/op
    3public class JdkBenchmarks {
    4
    5    @Benchmark
    6    @BenchmarkMode(AverageTime)
    7    @OutputTimeUnit(NANOSECONDS)
    8    public void indexed(Blackhole blackhole, TestState testState) {
    9        int length = testState.values.length;
    10        for(int i = 0; i &lt; length; i++) {
    11            blackhole.consume(testState.values[i]);
    12        }
    13    }
    14
    15    @Benchmark
    16    @BenchmarkMode(AverageTime)
    17    @OutputTimeUnit(NANOSECONDS)
    18    public void enhanced(Blackhole blackhole, TestState testState) {
    19        for (int value : testState.values) {
    20            blackhole.consume(value);
    21        }
    22    }
    23
    24
    25    @State(Scope.Benchmark)
    26    public static class TestState {
    27        public int[] values;
    28
    29        @Setup
    30        public void setupArray() {
    31            int count = 1000;
    32            values = new int[count];
    33            for(int i = 0; i &lt; count; i++) {
    34                values[i] = i;
    35            }
    36        }
    37    }
    38
    39    public static void main(String[] args) throws RunnerException {
    40        Options opt = new OptionsBuilder()
    41                .include(JdkBenchmarks.class.getSimpleName())
    42                .forks(1)
    43                .build();
    44
    45        new Runner(opt).run();
    46    }
    47
    48}
    49@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    50@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    51@Fork(3)
    52@BenchmarkMode(Mode.AverageTime)
    53@OutputTimeUnit(TimeUnit.NANOSECONDS)
    54@State(Scope.Benchmark)
    55public class JdkBenchmarks {
    56
    57    public int[] values;
    58
    59    @Setup
    60    public void setupArray() {
    61        int count = 1000;
    62        values = new int[count];
    63        for(int i = 0; i &lt; count; i++) {
    64            values[i] = i;
    65        }
    66    }
    67
    68    @Benchmark
    69    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    70    public void indexed(Blackhole bh) {
    71        for(int i = 0; i &lt; values.length; i++) {
    72            bh.consume(values[i]);
    73        }
    74    }
    75
    76    @Benchmark
    77    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    78    public void indexed_cached(Blackhole bh) {
    79        int[] vs = values;
    80        int length = vs.length;
    81        for(int i = 0; i &lt; length; i++) {
    82            bh.consume(vs[i]);
    83        }
    84    }
    85
    86    @Benchmark
    87    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    88    public void enhanced(Blackhole bh) {
    89        for (int value : values) {
    90            bh.consume(value);
    91        }
    92    }
    93}
    94

    Running both enhanced and indexed_cached under -prof perfasm reveals this hot loop (I specifically did @CompilerControl(DONT_INLINE) to let @Benchmark method be compiled alone, which makes an easier to digest perfasm output):

    1JdkBenchmarks.enhanced  avgt    5  2556.281 ±  31.789  ns/op
    2JdkBenchmarks.indexed   avgt    5  4032.164 ± 100.121  ns/op
    3public class JdkBenchmarks {
    4
    5    @Benchmark
    6    @BenchmarkMode(AverageTime)
    7    @OutputTimeUnit(NANOSECONDS)
    8    public void indexed(Blackhole blackhole, TestState testState) {
    9        int length = testState.values.length;
    10        for(int i = 0; i &lt; length; i++) {
    11            blackhole.consume(testState.values[i]);
    12        }
    13    }
    14
    15    @Benchmark
    16    @BenchmarkMode(AverageTime)
    17    @OutputTimeUnit(NANOSECONDS)
    18    public void enhanced(Blackhole blackhole, TestState testState) {
    19        for (int value : testState.values) {
    20            blackhole.consume(value);
    21        }
    22    }
    23
    24
    25    @State(Scope.Benchmark)
    26    public static class TestState {
    27        public int[] values;
    28
    29        @Setup
    30        public void setupArray() {
    31            int count = 1000;
    32            values = new int[count];
    33            for(int i = 0; i &lt; count; i++) {
    34                values[i] = i;
    35            }
    36        }
    37    }
    38
    39    public static void main(String[] args) throws RunnerException {
    40        Options opt = new OptionsBuilder()
    41                .include(JdkBenchmarks.class.getSimpleName())
    42                .forks(1)
    43                .build();
    44
    45        new Runner(opt).run();
    46    }
    47
    48}
    49@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    50@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    51@Fork(3)
    52@BenchmarkMode(Mode.AverageTime)
    53@OutputTimeUnit(TimeUnit.NANOSECONDS)
    54@State(Scope.Benchmark)
    55public class JdkBenchmarks {
    56
    57    public int[] values;
    58
    59    @Setup
    60    public void setupArray() {
    61        int count = 1000;
    62        values = new int[count];
    63        for(int i = 0; i &lt; count; i++) {
    64            values[i] = i;
    65        }
    66    }
    67
    68    @Benchmark
    69    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    70    public void indexed(Blackhole bh) {
    71        for(int i = 0; i &lt; values.length; i++) {
    72            bh.consume(values[i]);
    73        }
    74    }
    75
    76    @Benchmark
    77    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    78    public void indexed_cached(Blackhole bh) {
    79        int[] vs = values;
    80        int length = vs.length;
    81        for(int i = 0; i &lt; length; i++) {
    82            bh.consume(vs[i]);
    83        }
    84    }
    85
    86    @Benchmark
    87    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    88    public void enhanced(Blackhole bh) {
    89        for (int value : values) {
    90            bh.consume(value);
    91        }
    92    }
    93}
    94         ↗  0x...4240: mov  0x10(%r8,%rsi,4),%r10d  ; load values[i], blackhole it
    95 22.68%  │  0x...4245: mov  0x14(%r8,%rsi,4),%r11d  ; ... repeat 7 more times...
    96         │  0x...424a: mov  0x18(%r8,%rsi,4),%r10d  ;
    97 20.95%  │  0x...424f: mov  0x1c(%r8,%rsi,4),%r10d  ;
    98  0.02%  │  0x...4254: mov  0x20(%r8,%rsi,4),%r11d  ;
    99 24.73%  │  0x...4259: mov  0x24(%r8,%rsi,4),%r10d  ;
    100  0.24%  │  0x...425e: mov  0x28(%r8,%rsi,4),%r11d  ;
    101 20.04%  │  0x...4263: mov  0x2c(%r8,%rsi,4),%r10d  ; 
    102  0.22%  │  0x...4268: add  $0x8,%esi               ; i += 8
    103         │  0x...426b: cmp  %ebp,%esi               ; compare i with length (in %ebp)
    104  0.26%  ╰  0x...426d: jl   0x...4240               ; circle back if 8 more elements available
    105

    Very efficient!

    Running indexed with -prof perfasm reveals:

    1JdkBenchmarks.enhanced  avgt    5  2556.281 ±  31.789  ns/op
    2JdkBenchmarks.indexed   avgt    5  4032.164 ± 100.121  ns/op
    3public class JdkBenchmarks {
    4
    5    @Benchmark
    6    @BenchmarkMode(AverageTime)
    7    @OutputTimeUnit(NANOSECONDS)
    8    public void indexed(Blackhole blackhole, TestState testState) {
    9        int length = testState.values.length;
    10        for(int i = 0; i &lt; length; i++) {
    11            blackhole.consume(testState.values[i]);
    12        }
    13    }
    14
    15    @Benchmark
    16    @BenchmarkMode(AverageTime)
    17    @OutputTimeUnit(NANOSECONDS)
    18    public void enhanced(Blackhole blackhole, TestState testState) {
    19        for (int value : testState.values) {
    20            blackhole.consume(value);
    21        }
    22    }
    23
    24
    25    @State(Scope.Benchmark)
    26    public static class TestState {
    27        public int[] values;
    28
    29        @Setup
    30        public void setupArray() {
    31            int count = 1000;
    32            values = new int[count];
    33            for(int i = 0; i &lt; count; i++) {
    34                values[i] = i;
    35            }
    36        }
    37    }
    38
    39    public static void main(String[] args) throws RunnerException {
    40        Options opt = new OptionsBuilder()
    41                .include(JdkBenchmarks.class.getSimpleName())
    42                .forks(1)
    43                .build();
    44
    45        new Runner(opt).run();
    46    }
    47
    48}
    49@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    50@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    51@Fork(3)
    52@BenchmarkMode(Mode.AverageTime)
    53@OutputTimeUnit(TimeUnit.NANOSECONDS)
    54@State(Scope.Benchmark)
    55public class JdkBenchmarks {
    56
    57    public int[] values;
    58
    59    @Setup
    60    public void setupArray() {
    61        int count = 1000;
    62        values = new int[count];
    63        for(int i = 0; i &lt; count; i++) {
    64            values[i] = i;
    65        }
    66    }
    67
    68    @Benchmark
    69    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    70    public void indexed(Blackhole bh) {
    71        for(int i = 0; i &lt; values.length; i++) {
    72            bh.consume(values[i]);
    73        }
    74    }
    75
    76    @Benchmark
    77    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    78    public void indexed_cached(Blackhole bh) {
    79        int[] vs = values;
    80        int length = vs.length;
    81        for(int i = 0; i &lt; length; i++) {
    82            bh.consume(vs[i]);
    83        }
    84    }
    85
    86    @Benchmark
    87    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    88    public void enhanced(Blackhole bh) {
    89        for (int value : values) {
    90            bh.consume(value);
    91        }
    92    }
    93}
    94         ↗  0x...4240: mov  0x10(%r8,%rsi,4),%r10d  ; load values[i], blackhole it
    95 22.68%  │  0x...4245: mov  0x14(%r8,%rsi,4),%r11d  ; ... repeat 7 more times...
    96         │  0x...424a: mov  0x18(%r8,%rsi,4),%r10d  ;
    97 20.95%  │  0x...424f: mov  0x1c(%r8,%rsi,4),%r10d  ;
    98  0.02%  │  0x...4254: mov  0x20(%r8,%rsi,4),%r11d  ;
    99 24.73%  │  0x...4259: mov  0x24(%r8,%rsi,4),%r10d  ;
    100  0.24%  │  0x...425e: mov  0x28(%r8,%rsi,4),%r11d  ;
    101 20.04%  │  0x...4263: mov  0x2c(%r8,%rsi,4),%r10d  ; 
    102  0.22%  │  0x...4268: add  $0x8,%esi               ; i += 8
    103         │  0x...426b: cmp  %ebp,%esi               ; compare i with length (in %ebp)
    104  0.26%  ╰  0x...426d: jl   0x...4240               ; circle back if 8 more elements available
    105         ↗  0x...4170: mov  0xc(%r12,%r8,8),%r9d    ; array bounds check, load values.length
    106  3.42%  │  0x...4175: cmp  %r9d,%r10d              ; array bounds check, compare i
    107 16.02%  │  0x...4178: jae  0x...41b1               ;  failed? jump to exception handling
    108         │  0x...417a: lea  (%r12,%r8,8),%r11       ; load values[i], part 1
    109  0.04%  │  0x...417e: mov  0x10(%r11,%r10,4),%r11d ; load values[i], part 2
    110         │                                          ; %r11d is blackholed
    111 35.69%  │  0x...4183: mov  0xc(%rsi),%r8d          ; get &quot;values&quot;
    112  0.71%  │  0x...4187: mov  0x348(%r15),%r11        ; safepoint poll, part 1 (JVM infra)
    113  4.03%  │  0x...418e: inc  %r10d                   ; i++
    114  0.12%  │  0x...4191: test %eax,(%r11)             ; safepoint poll, part 2 (JVM infra)
    115 27.74%  │  0x...4194: mov  0xc(%r12,%r8,8),%r9d    ; load values.length
    116  8.53%  │  0x...4199: cmp  %r9d,%r10d              ; check i &lt; values.length
    117  0.24%  ╰  0x...419c: jl   0x...4170               ; circle back if more 
    118

    This is because Blackhole.consume call is opaque to the compiler (like many other non-inlined calls), so it has to conservatively presume that values can change in the middle of the loop!

    Which means, compiler cannot stash values in a register, it cannot trust the array bounds check to always succeed, it cannot even guarantee the loop terminates (hence safepoint polls), and on top of that, loop unrolling does not want to multiply that per-element mess even more.

    So you get the penalty like this (TR 3970X, JDK 17.0.2 EA, Linux x86_64):

    1JdkBenchmarks.enhanced  avgt    5  2556.281 ±  31.789  ns/op
    2JdkBenchmarks.indexed   avgt    5  4032.164 ± 100.121  ns/op
    3public class JdkBenchmarks {
    4
    5    @Benchmark
    6    @BenchmarkMode(AverageTime)
    7    @OutputTimeUnit(NANOSECONDS)
    8    public void indexed(Blackhole blackhole, TestState testState) {
    9        int length = testState.values.length;
    10        for(int i = 0; i &lt; length; i++) {
    11            blackhole.consume(testState.values[i]);
    12        }
    13    }
    14
    15    @Benchmark
    16    @BenchmarkMode(AverageTime)
    17    @OutputTimeUnit(NANOSECONDS)
    18    public void enhanced(Blackhole blackhole, TestState testState) {
    19        for (int value : testState.values) {
    20            blackhole.consume(value);
    21        }
    22    }
    23
    24
    25    @State(Scope.Benchmark)
    26    public static class TestState {
    27        public int[] values;
    28
    29        @Setup
    30        public void setupArray() {
    31            int count = 1000;
    32            values = new int[count];
    33            for(int i = 0; i &lt; count; i++) {
    34                values[i] = i;
    35            }
    36        }
    37    }
    38
    39    public static void main(String[] args) throws RunnerException {
    40        Options opt = new OptionsBuilder()
    41                .include(JdkBenchmarks.class.getSimpleName())
    42                .forks(1)
    43                .build();
    44
    45        new Runner(opt).run();
    46    }
    47
    48}
    49@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    50@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    51@Fork(3)
    52@BenchmarkMode(Mode.AverageTime)
    53@OutputTimeUnit(TimeUnit.NANOSECONDS)
    54@State(Scope.Benchmark)
    55public class JdkBenchmarks {
    56
    57    public int[] values;
    58
    59    @Setup
    60    public void setupArray() {
    61        int count = 1000;
    62        values = new int[count];
    63        for(int i = 0; i &lt; count; i++) {
    64            values[i] = i;
    65        }
    66    }
    67
    68    @Benchmark
    69    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    70    public void indexed(Blackhole bh) {
    71        for(int i = 0; i &lt; values.length; i++) {
    72            bh.consume(values[i]);
    73        }
    74    }
    75
    76    @Benchmark
    77    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    78    public void indexed_cached(Blackhole bh) {
    79        int[] vs = values;
    80        int length = vs.length;
    81        for(int i = 0; i &lt; length; i++) {
    82            bh.consume(vs[i]);
    83        }
    84    }
    85
    86    @Benchmark
    87    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    88    public void enhanced(Blackhole bh) {
    89        for (int value : values) {
    90            bh.consume(value);
    91        }
    92    }
    93}
    94         ↗  0x...4240: mov  0x10(%r8,%rsi,4),%r10d  ; load values[i], blackhole it
    95 22.68%  │  0x...4245: mov  0x14(%r8,%rsi,4),%r11d  ; ... repeat 7 more times...
    96         │  0x...424a: mov  0x18(%r8,%rsi,4),%r10d  ;
    97 20.95%  │  0x...424f: mov  0x1c(%r8,%rsi,4),%r10d  ;
    98  0.02%  │  0x...4254: mov  0x20(%r8,%rsi,4),%r11d  ;
    99 24.73%  │  0x...4259: mov  0x24(%r8,%rsi,4),%r10d  ;
    100  0.24%  │  0x...425e: mov  0x28(%r8,%rsi,4),%r11d  ;
    101 20.04%  │  0x...4263: mov  0x2c(%r8,%rsi,4),%r10d  ; 
    102  0.22%  │  0x...4268: add  $0x8,%esi               ; i += 8
    103         │  0x...426b: cmp  %ebp,%esi               ; compare i with length (in %ebp)
    104  0.26%  ╰  0x...426d: jl   0x...4240               ; circle back if 8 more elements available
    105         ↗  0x...4170: mov  0xc(%r12,%r8,8),%r9d    ; array bounds check, load values.length
    106  3.42%  │  0x...4175: cmp  %r9d,%r10d              ; array bounds check, compare i
    107 16.02%  │  0x...4178: jae  0x...41b1               ;  failed? jump to exception handling
    108         │  0x...417a: lea  (%r12,%r8,8),%r11       ; load values[i], part 1
    109  0.04%  │  0x...417e: mov  0x10(%r11,%r10,4),%r11d ; load values[i], part 2
    110         │                                          ; %r11d is blackholed
    111 35.69%  │  0x...4183: mov  0xc(%rsi),%r8d          ; get &quot;values&quot;
    112  0.71%  │  0x...4187: mov  0x348(%r15),%r11        ; safepoint poll, part 1 (JVM infra)
    113  4.03%  │  0x...418e: inc  %r10d                   ; i++
    114  0.12%  │  0x...4191: test %eax,(%r11)             ; safepoint poll, part 2 (JVM infra)
    115 27.74%  │  0x...4194: mov  0xc(%r12,%r8,8),%r9d    ; load values.length
    116  8.53%  │  0x...4199: cmp  %r9d,%r10d              ; check i &lt; values.length
    117  0.24%  ╰  0x...419c: jl   0x...4170               ; circle back if more 
    118Benchmark                     Mode  Cnt     Score   Error  Units
    119JdkBenchmarks.enhanced        avgt    5   144.962 ± 0.918  ns/op
    120JdkBenchmarks.indexed         avgt    5  1030.981 ± 3.775  ns/op ; + 880 ns/op!
    121JdkBenchmarks.indexed_cached  avgt    5   144.799 ± 0.643  ns/op ; same as enhanced
    122

    Additional fun part:

    On most JDKs the dominating costs are the costs of calling the Blackhole.consume in this test. Compared to the cost of array access, the cost of Java-style Blackhole is quite bad. With JDK 17+ and JMH 1.34, the compiler Blackholes would be used, and thus provide much more fidelity for the test.

    Without compiler blackholes, the effect hides in the Blackhole overhead nearly completely (>25x overhead means we can execute a lot of bad code preceding the Blackhole call!):

    1JdkBenchmarks.enhanced  avgt    5  2556.281 ±  31.789  ns/op
    2JdkBenchmarks.indexed   avgt    5  4032.164 ± 100.121  ns/op
    3public class JdkBenchmarks {
    4
    5    @Benchmark
    6    @BenchmarkMode(AverageTime)
    7    @OutputTimeUnit(NANOSECONDS)
    8    public void indexed(Blackhole blackhole, TestState testState) {
    9        int length = testState.values.length;
    10        for(int i = 0; i &lt; length; i++) {
    11            blackhole.consume(testState.values[i]);
    12        }
    13    }
    14
    15    @Benchmark
    16    @BenchmarkMode(AverageTime)
    17    @OutputTimeUnit(NANOSECONDS)
    18    public void enhanced(Blackhole blackhole, TestState testState) {
    19        for (int value : testState.values) {
    20            blackhole.consume(value);
    21        }
    22    }
    23
    24
    25    @State(Scope.Benchmark)
    26    public static class TestState {
    27        public int[] values;
    28
    29        @Setup
    30        public void setupArray() {
    31            int count = 1000;
    32            values = new int[count];
    33            for(int i = 0; i &lt; count; i++) {
    34                values[i] = i;
    35            }
    36        }
    37    }
    38
    39    public static void main(String[] args) throws RunnerException {
    40        Options opt = new OptionsBuilder()
    41                .include(JdkBenchmarks.class.getSimpleName())
    42                .forks(1)
    43                .build();
    44
    45        new Runner(opt).run();
    46    }
    47
    48}
    49@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    50@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    51@Fork(3)
    52@BenchmarkMode(Mode.AverageTime)
    53@OutputTimeUnit(TimeUnit.NANOSECONDS)
    54@State(Scope.Benchmark)
    55public class JdkBenchmarks {
    56
    57    public int[] values;
    58
    59    @Setup
    60    public void setupArray() {
    61        int count = 1000;
    62        values = new int[count];
    63        for(int i = 0; i &lt; count; i++) {
    64            values[i] = i;
    65        }
    66    }
    67
    68    @Benchmark
    69    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    70    public void indexed(Blackhole bh) {
    71        for(int i = 0; i &lt; values.length; i++) {
    72            bh.consume(values[i]);
    73        }
    74    }
    75
    76    @Benchmark
    77    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    78    public void indexed_cached(Blackhole bh) {
    79        int[] vs = values;
    80        int length = vs.length;
    81        for(int i = 0; i &lt; length; i++) {
    82            bh.consume(vs[i]);
    83        }
    84    }
    85
    86    @Benchmark
    87    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    88    public void enhanced(Blackhole bh) {
    89        for (int value : values) {
    90            bh.consume(value);
    91        }
    92    }
    93}
    94         ↗  0x...4240: mov  0x10(%r8,%rsi,4),%r10d  ; load values[i], blackhole it
    95 22.68%  │  0x...4245: mov  0x14(%r8,%rsi,4),%r11d  ; ... repeat 7 more times...
    96         │  0x...424a: mov  0x18(%r8,%rsi,4),%r10d  ;
    97 20.95%  │  0x...424f: mov  0x1c(%r8,%rsi,4),%r10d  ;
    98  0.02%  │  0x...4254: mov  0x20(%r8,%rsi,4),%r11d  ;
    99 24.73%  │  0x...4259: mov  0x24(%r8,%rsi,4),%r10d  ;
    100  0.24%  │  0x...425e: mov  0x28(%r8,%rsi,4),%r11d  ;
    101 20.04%  │  0x...4263: mov  0x2c(%r8,%rsi,4),%r10d  ; 
    102  0.22%  │  0x...4268: add  $0x8,%esi               ; i += 8
    103         │  0x...426b: cmp  %ebp,%esi               ; compare i with length (in %ebp)
    104  0.26%  ╰  0x...426d: jl   0x...4240               ; circle back if 8 more elements available
    105         ↗  0x...4170: mov  0xc(%r12,%r8,8),%r9d    ; array bounds check, load values.length
    106  3.42%  │  0x...4175: cmp  %r9d,%r10d              ; array bounds check, compare i
    107 16.02%  │  0x...4178: jae  0x...41b1               ;  failed? jump to exception handling
    108         │  0x...417a: lea  (%r12,%r8,8),%r11       ; load values[i], part 1
    109  0.04%  │  0x...417e: mov  0x10(%r11,%r10,4),%r11d ; load values[i], part 2
    110         │                                          ; %r11d is blackholed
    111 35.69%  │  0x...4183: mov  0xc(%rsi),%r8d          ; get &quot;values&quot;
    112  0.71%  │  0x...4187: mov  0x348(%r15),%r11        ; safepoint poll, part 1 (JVM infra)
    113  4.03%  │  0x...418e: inc  %r10d                   ; i++
    114  0.12%  │  0x...4191: test %eax,(%r11)             ; safepoint poll, part 2 (JVM infra)
    115 27.74%  │  0x...4194: mov  0xc(%r12,%r8,8),%r9d    ; load values.length
    116  8.53%  │  0x...4199: cmp  %r9d,%r10d              ; check i &lt; values.length
    117  0.24%  ╰  0x...419c: jl   0x...4170               ; circle back if more 
    118Benchmark                     Mode  Cnt     Score   Error  Units
    119JdkBenchmarks.enhanced        avgt    5   144.962 ± 0.918  ns/op
    120JdkBenchmarks.indexed         avgt    5  1030.981 ± 3.775  ns/op ; + 880 ns/op!
    121JdkBenchmarks.indexed_cached  avgt    5   144.799 ± 0.643  ns/op ; same as enhanced
    122Benchmark                     Mode  Cnt     Score   Error  Units
    123JdkBenchmarks.enhanced        avgt    5  4062.866 ± 4.736  ns/op
    124JdkBenchmarks.indexed         avgt    5  4071.620 ± 1.057  ns/op ; + 10 ns/op [whoops]
    125JdkBenchmarks.indexed_cached  avgt    5  4061.390 ± 0.692  ns/op ; same as enhanced
    126

    It would re-manifest if we drop @CompilerControl(DONT_INLINE), because the resulting generated code would be much messier:

    1JdkBenchmarks.enhanced  avgt    5  2556.281 ±  31.789  ns/op
    2JdkBenchmarks.indexed   avgt    5  4032.164 ± 100.121  ns/op
    3public class JdkBenchmarks {
    4
    5    @Benchmark
    6    @BenchmarkMode(AverageTime)
    7    @OutputTimeUnit(NANOSECONDS)
    8    public void indexed(Blackhole blackhole, TestState testState) {
    9        int length = testState.values.length;
    10        for(int i = 0; i &lt; length; i++) {
    11            blackhole.consume(testState.values[i]);
    12        }
    13    }
    14
    15    @Benchmark
    16    @BenchmarkMode(AverageTime)
    17    @OutputTimeUnit(NANOSECONDS)
    18    public void enhanced(Blackhole blackhole, TestState testState) {
    19        for (int value : testState.values) {
    20            blackhole.consume(value);
    21        }
    22    }
    23
    24
    25    @State(Scope.Benchmark)
    26    public static class TestState {
    27        public int[] values;
    28
    29        @Setup
    30        public void setupArray() {
    31            int count = 1000;
    32            values = new int[count];
    33            for(int i = 0; i &lt; count; i++) {
    34                values[i] = i;
    35            }
    36        }
    37    }
    38
    39    public static void main(String[] args) throws RunnerException {
    40        Options opt = new OptionsBuilder()
    41                .include(JdkBenchmarks.class.getSimpleName())
    42                .forks(1)
    43                .build();
    44
    45        new Runner(opt).run();
    46    }
    47
    48}
    49@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    50@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
    51@Fork(3)
    52@BenchmarkMode(Mode.AverageTime)
    53@OutputTimeUnit(TimeUnit.NANOSECONDS)
    54@State(Scope.Benchmark)
    55public class JdkBenchmarks {
    56
    57    public int[] values;
    58
    59    @Setup
    60    public void setupArray() {
    61        int count = 1000;
    62        values = new int[count];
    63        for(int i = 0; i &lt; count; i++) {
    64            values[i] = i;
    65        }
    66    }
    67
    68    @Benchmark
    69    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    70    public void indexed(Blackhole bh) {
    71        for(int i = 0; i &lt; values.length; i++) {
    72            bh.consume(values[i]);
    73        }
    74    }
    75
    76    @Benchmark
    77    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    78    public void indexed_cached(Blackhole bh) {
    79        int[] vs = values;
    80        int length = vs.length;
    81        for(int i = 0; i &lt; length; i++) {
    82            bh.consume(vs[i]);
    83        }
    84    }
    85
    86    @Benchmark
    87    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    88    public void enhanced(Blackhole bh) {
    89        for (int value : values) {
    90            bh.consume(value);
    91        }
    92    }
    93}
    94         ↗  0x...4240: mov  0x10(%r8,%rsi,4),%r10d  ; load values[i], blackhole it
    95 22.68%  │  0x...4245: mov  0x14(%r8,%rsi,4),%r11d  ; ... repeat 7 more times...
    96         │  0x...424a: mov  0x18(%r8,%rsi,4),%r10d  ;
    97 20.95%  │  0x...424f: mov  0x1c(%r8,%rsi,4),%r10d  ;
    98  0.02%  │  0x...4254: mov  0x20(%r8,%rsi,4),%r11d  ;
    99 24.73%  │  0x...4259: mov  0x24(%r8,%rsi,4),%r10d  ;
    100  0.24%  │  0x...425e: mov  0x28(%r8,%rsi,4),%r11d  ;
    101 20.04%  │  0x...4263: mov  0x2c(%r8,%rsi,4),%r10d  ; 
    102  0.22%  │  0x...4268: add  $0x8,%esi               ; i += 8
    103         │  0x...426b: cmp  %ebp,%esi               ; compare i with length (in %ebp)
    104  0.26%  ╰  0x...426d: jl   0x...4240               ; circle back if 8 more elements available
    105         ↗  0x...4170: mov  0xc(%r12,%r8,8),%r9d    ; array bounds check, load values.length
    106  3.42%  │  0x...4175: cmp  %r9d,%r10d              ; array bounds check, compare i
    107 16.02%  │  0x...4178: jae  0x...41b1               ;  failed? jump to exception handling
    108         │  0x...417a: lea  (%r12,%r8,8),%r11       ; load values[i], part 1
    109  0.04%  │  0x...417e: mov  0x10(%r11,%r10,4),%r11d ; load values[i], part 2
    110         │                                          ; %r11d is blackholed
    111 35.69%  │  0x...4183: mov  0xc(%rsi),%r8d          ; get &quot;values&quot;
    112  0.71%  │  0x...4187: mov  0x348(%r15),%r11        ; safepoint poll, part 1 (JVM infra)
    113  4.03%  │  0x...418e: inc  %r10d                   ; i++
    114  0.12%  │  0x...4191: test %eax,(%r11)             ; safepoint poll, part 2 (JVM infra)
    115 27.74%  │  0x...4194: mov  0xc(%r12,%r8,8),%r9d    ; load values.length
    116  8.53%  │  0x...4199: cmp  %r9d,%r10d              ; check i &lt; values.length
    117  0.24%  ╰  0x...419c: jl   0x...4170               ; circle back if more 
    118Benchmark                     Mode  Cnt     Score   Error  Units
    119JdkBenchmarks.enhanced        avgt    5   144.962 ± 0.918  ns/op
    120JdkBenchmarks.indexed         avgt    5  1030.981 ± 3.775  ns/op ; + 880 ns/op!
    121JdkBenchmarks.indexed_cached  avgt    5   144.799 ± 0.643  ns/op ; same as enhanced
    122Benchmark                     Mode  Cnt     Score   Error  Units
    123JdkBenchmarks.enhanced        avgt    5  4062.866 ± 4.736  ns/op
    124JdkBenchmarks.indexed         avgt    5  4071.620 ± 1.057  ns/op ; + 10 ns/op [whoops]
    125JdkBenchmarks.indexed_cached  avgt    5  4061.390 ± 0.692  ns/op ; same as enhanced
    126Benchmark                     Mode  Cnt     Score    Error  Units
    127JdkBenchmarks.enhanced        avgt    5  4067.118 ± 40.699  ns/op
    128JdkBenchmarks.indexed         avgt    5  4601.370 ±  0.632  ns/op ; + 530 ns/op
    129JdkBenchmarks.indexed_cached  avgt    5  4064.455 ±  1.554  ns/op ; same as enhanced
    130

    Source https://stackoverflow.com/questions/70583053

    QUESTION

    solidity TypeError: Object of type set is not JSON serializable

    Asked 2021-Dec-29 at 07:57

    I ran the code in VSCode and got a TypeError: Object of type set is not JSON serializable. I just start to learn to code, really don't get it, and googled it, also didn't know what does JSON serializable means.

    1from solcx import compile_standard
    2import json
    3
    4# get the contract content
    5with open(&quot;./SimpleStorage.sol&quot;, &quot;r&quot;) as file:
    6    simple_storage_file = file.read()
    7
    8# compile the contract
    9
    10compiled_sol = compile_standard(
    11    {
    12        &quot;language&quot;: &quot;Solidity&quot;,
    13        &quot;sources&quot;: {&quot;SimpleStorage.sol&quot;: {&quot;content&quot;: simple_storage_file}},
    14        &quot;settings&quot;: {
    15            &quot;outputSelection&quot;: {
    16                &quot;*&quot;: {
    17                    &quot;*&quot;: {&quot;abi&quot;, &quot;metadata&quot;, &quot;evm.bytecode&quot;, &quot;evm.bytecode.sourceMap&quot;}
    18                }
    19            }
    20        },
    21    },
    22    solc_version=&quot;0.6.0&quot;,
    23)
    24
    25# creat json file dump the comiled code in it to make it more readable.
    26with open(&quot;compiled_code.json&quot;, &quot;w&quot;) as file:
    27    json.dump(compiled_sol, file)
    28
    29print(compiled_sol)
    30

    The full error information is below:

    1from solcx import compile_standard
    2import json
    3
    4# get the contract content
    5with open(&quot;./SimpleStorage.sol&quot;, &quot;r&quot;) as file:
    6    simple_storage_file = file.read()
    7
    8# compile the contract
    9
    10compiled_sol = compile_standard(
    11    {
    12        &quot;language&quot;: &quot;Solidity&quot;,
    13        &quot;sources&quot;: {&quot;SimpleStorage.sol&quot;: {&quot;content&quot;: simple_storage_file}},
    14        &quot;settings&quot;: {
    15            &quot;outputSelection&quot;: {
    16                &quot;*&quot;: {
    17                    &quot;*&quot;: {&quot;abi&quot;, &quot;metadata&quot;, &quot;evm.bytecode&quot;, &quot;evm.bytecode.sourceMap&quot;}
    18                }
    19            }
    20        },
    21    },
    22    solc_version=&quot;0.6.0&quot;,
    23)
    24
    25# creat json file dump the comiled code in it to make it more readable.
    26with open(&quot;compiled_code.json&quot;, &quot;w&quot;) as file:
    27    json.dump(compiled_sol, file)
    28
    29print(compiled_sol)
    30(env) (base) liwei@liweideMacBook-Pro practice % python3 deploy.py
    31Traceback (most recent call last):
    32  File &quot;deploy.py&quot;, line 10, in &lt;module&gt;
    33    compiled_sol = compile_standard(
    34  File &quot;/Users/liwei/Desktop/demos/practice/env/lib/python3.8/site-packages/solcx/main.py&quot;, line 375, in compile_standard
    35    stdin=json.dumps(input_data),
    36  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/__init__.py&quot;, line 231, in dumps
    37    return _default_encoder.encode(obj)
    38  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/encoder.py&quot;, line 199, in encode
    39    chunks = self.iterencode(o, _one_shot=True)
    40  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/encoder.py&quot;, line 257, in iterencode
    41    return _iterencode(o, 0)
    42  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/encoder.py&quot;, line 179, in default
    43    raise TypeError(f'Object of type {o.__class__.__name__} '
    44TypeError: Object of type set is not JSON serializable
    45

    ANSWER

    Answered 2021-Dec-29 at 01:48

    Instead of this:

    1from solcx import compile_standard
    2import json
    3
    4# get the contract content
    5with open(&quot;./SimpleStorage.sol&quot;, &quot;r&quot;) as file:
    6    simple_storage_file = file.read()
    7
    8# compile the contract
    9
    10compiled_sol = compile_standard(
    11    {
    12        &quot;language&quot;: &quot;Solidity&quot;,
    13        &quot;sources&quot;: {&quot;SimpleStorage.sol&quot;: {&quot;content&quot;: simple_storage_file}},
    14        &quot;settings&quot;: {
    15            &quot;outputSelection&quot;: {
    16                &quot;*&quot;: {
    17                    &quot;*&quot;: {&quot;abi&quot;, &quot;metadata&quot;, &quot;evm.bytecode&quot;, &quot;evm.bytecode.sourceMap&quot;}
    18                }
    19            }
    20        },
    21    },
    22    solc_version=&quot;0.6.0&quot;,
    23)
    24
    25# creat json file dump the comiled code in it to make it more readable.
    26with open(&quot;compiled_code.json&quot;, &quot;w&quot;) as file:
    27    json.dump(compiled_sol, file)
    28
    29print(compiled_sol)
    30(env) (base) liwei@liweideMacBook-Pro practice % python3 deploy.py
    31Traceback (most recent call last):
    32  File &quot;deploy.py&quot;, line 10, in &lt;module&gt;
    33    compiled_sol = compile_standard(
    34  File &quot;/Users/liwei/Desktop/demos/practice/env/lib/python3.8/site-packages/solcx/main.py&quot;, line 375, in compile_standard
    35    stdin=json.dumps(input_data),
    36  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/__init__.py&quot;, line 231, in dumps
    37    return _default_encoder.encode(obj)
    38  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/encoder.py&quot;, line 199, in encode
    39    chunks = self.iterencode(o, _one_shot=True)
    40  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/encoder.py&quot;, line 257, in iterencode
    41    return _iterencode(o, 0)
    42  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/encoder.py&quot;, line 179, in default
    43    raise TypeError(f'Object of type {o.__class__.__name__} '
    44TypeError: Object of type set is not JSON serializable
    45{&quot;abi&quot;, &quot;metadata&quot;, &quot;evm.bytecode&quot;, &quot;evm.bytecode.sourceMap&quot;}
    46

    you should use this:

    1from solcx import compile_standard
    2import json
    3
    4# get the contract content
    5with open(&quot;./SimpleStorage.sol&quot;, &quot;r&quot;) as file:
    6    simple_storage_file = file.read()
    7
    8# compile the contract
    9
    10compiled_sol = compile_standard(
    11    {
    12        &quot;language&quot;: &quot;Solidity&quot;,
    13        &quot;sources&quot;: {&quot;SimpleStorage.sol&quot;: {&quot;content&quot;: simple_storage_file}},
    14        &quot;settings&quot;: {
    15            &quot;outputSelection&quot;: {
    16                &quot;*&quot;: {
    17                    &quot;*&quot;: {&quot;abi&quot;, &quot;metadata&quot;, &quot;evm.bytecode&quot;, &quot;evm.bytecode.sourceMap&quot;}
    18                }
    19            }
    20        },
    21    },
    22    solc_version=&quot;0.6.0&quot;,
    23)
    24
    25# creat json file dump the comiled code in it to make it more readable.
    26with open(&quot;compiled_code.json&quot;, &quot;w&quot;) as file:
    27    json.dump(compiled_sol, file)
    28
    29print(compiled_sol)
    30(env) (base) liwei@liweideMacBook-Pro practice % python3 deploy.py
    31Traceback (most recent call last):
    32  File &quot;deploy.py&quot;, line 10, in &lt;module&gt;
    33    compiled_sol = compile_standard(
    34  File &quot;/Users/liwei/Desktop/demos/practice/env/lib/python3.8/site-packages/solcx/main.py&quot;, line 375, in compile_standard
    35    stdin=json.dumps(input_data),
    36  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/__init__.py&quot;, line 231, in dumps
    37    return _default_encoder.encode(obj)
    38  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/encoder.py&quot;, line 199, in encode
    39    chunks = self.iterencode(o, _one_shot=True)
    40  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/encoder.py&quot;, line 257, in iterencode
    41    return _iterencode(o, 0)
    42  File &quot;/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/json/encoder.py&quot;, line 179, in default
    43    raise TypeError(f'Object of type {o.__class__.__name__} '
    44TypeError: Object of type set is not JSON serializable
    45{&quot;abi&quot;, &quot;metadata&quot;, &quot;evm.bytecode&quot;, &quot;evm.bytecode.sourceMap&quot;}
    46[&quot;abi&quot;, &quot;metadata&quot;, &quot;evm.bytecode&quot;, &quot;evm.bytecode.sourceMap&quot;]
    47

    Sets in Python aren't JSON serializable.

    Source https://stackoverflow.com/questions/70514336

    QUESTION

    JDK 17: Switch statement causes java.lang.VerifyError: Bad type on operand stack

    Asked 2021-Oct-26 at 09:25

    Just tried JDK17 on Eclipse 2021-09 to have it fail with a java.lang.VerifyError, which wasn't very helpful itself. I tracked it down to a switch statement, that gets fed a value pulled out of a Map or another generic type. If I use a local variable in the switch statement instead, everything works as intended.

    Test code:

    1import java.util.HashMap;
    2import java.util.Map;
    3
    4public class SwitchFail {
    5  public static void main(String[] args) {
    6    //doesnt work
    7    Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    8    stringMap.put(1, &quot;Test&quot;);
    9    switch(stringMap.get(1)) {
    10    }
    11
    12    //works
    13    String plainString = &quot;Test&quot;;
    14     switch(plainString) {
    15    }
    16  }
    17}
    18

    This throws the following error:

    1import java.util.HashMap;
    2import java.util.Map;
    3
    4public class SwitchFail {
    5  public static void main(String[] args) {
    6    //doesnt work
    7    Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    8    stringMap.put(1, &quot;Test&quot;);
    9    switch(stringMap.get(1)) {
    10    }
    11
    12    //works
    13    String plainString = &quot;Test&quot;;
    14     switch(plainString) {
    15    }
    16  }
    17}
    18Error: Unable to initialize main class SwitchFail
    19Caused by: java.lang.VerifyError: Bad type on operand stack
    20Exception Details:
    21  Location:
    22    SwitchFail.main([Ljava/lang/String;)V @33: invokevirtual
    23  Reason:
    24    Type 'java/lang/Object' (current frame, stack[0]) is not assignable to 'java/lang/String'
    25  Current Frame:
    26    bci: @33
    27    flags: { }
    28    locals: { '[Ljava/lang/String;', 'java/util/HashMap', 'java/lang/Object' }
    29    stack: { 'java/lang/Object' }
    30  Bytecode:
    31    0000000: bb00 1059 b700 124c 2b04 b800 1312 19b9
    32    0000010: 001b 0300 572b 04b8 0013 b900 2102 0059
    33    0000020: 4db6 0025 57b1  
    34
    35                   
    36            
    37

    Didn't try another JDK between 11 and 17 yet. Switches gained some new functions between those versions, so that might be it. Maybe it's a problem in the Eclipse JDT or my local JDK, so any tries to reproduce this error on another configuration or IDE would be great. Tried on OpenJDK (build 17+35-2724) for macOS.

    Edit: Also happens on

    1import java.util.HashMap;
    2import java.util.Map;
    3
    4public class SwitchFail {
    5  public static void main(String[] args) {
    6    //doesnt work
    7    Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    8    stringMap.put(1, &quot;Test&quot;);
    9    switch(stringMap.get(1)) {
    10    }
    11
    12    //works
    13    String plainString = &quot;Test&quot;;
    14     switch(plainString) {
    15    }
    16  }
    17}
    18Error: Unable to initialize main class SwitchFail
    19Caused by: java.lang.VerifyError: Bad type on operand stack
    20Exception Details:
    21  Location:
    22    SwitchFail.main([Ljava/lang/String;)V @33: invokevirtual
    23  Reason:
    24    Type 'java/lang/Object' (current frame, stack[0]) is not assignable to 'java/lang/String'
    25  Current Frame:
    26    bci: @33
    27    flags: { }
    28    locals: { '[Ljava/lang/String;', 'java/util/HashMap', 'java/lang/Object' }
    29    stack: { 'java/lang/Object' }
    30  Bytecode:
    31    0000000: bb00 1059 b700 124c 2b04 b800 1312 19b9
    32    0000010: 001b 0300 572b 04b8 0013 b900 2102 0059
    33    0000020: 4db6 0025 57b1  
    34
    35                   
    36            
    37List&lt;String&gt; stringList = Arrays.asList(&quot;Test&quot;);
    38switch(stringList.get(0)) {}
    39

    Most likely an issue with the new JDT for Java 17 or my local installation.

    ANSWER

    Answered 2021-Oct-26 at 09:25

    It is a problem with your Eclipse, not with Java-17 itself. Java-17 has been released only yesterday. Wait for some time until the IDEs are updated to support Java-17.

    Demo:

    1import java.util.HashMap;
    2import java.util.Map;
    3
    4public class SwitchFail {
    5  public static void main(String[] args) {
    6    //doesnt work
    7    Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    8    stringMap.put(1, &quot;Test&quot;);
    9    switch(stringMap.get(1)) {
    10    }
    11
    12    //works
    13    String plainString = &quot;Test&quot;;
    14     switch(plainString) {
    15    }
    16  }
    17}
    18Error: Unable to initialize main class SwitchFail
    19Caused by: java.lang.VerifyError: Bad type on operand stack
    20Exception Details:
    21  Location:
    22    SwitchFail.main([Ljava/lang/String;)V @33: invokevirtual
    23  Reason:
    24    Type 'java/lang/Object' (current frame, stack[0]) is not assignable to 'java/lang/String'
    25  Current Frame:
    26    bci: @33
    27    flags: { }
    28    locals: { '[Ljava/lang/String;', 'java/util/HashMap', 'java/lang/Object' }
    29    stack: { 'java/lang/Object' }
    30  Bytecode:
    31    0000000: bb00 1059 b700 124c 2b04 b800 1312 19b9
    32    0000010: 001b 0300 572b 04b8 0013 b900 2102 0059
    33    0000020: 4db6 0025 57b1  
    34
    35                   
    36            
    37List&lt;String&gt; stringList = Arrays.asList(&quot;Test&quot;);
    38switch(stringList.get(0)) {}
    39import java.util.HashMap;
    40import java.util.Map;
    41
    42public class SwitchFail {
    43    public static void main(String[] args) {
    44        Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    45        stringMap.put(1, &quot;Test&quot;);
    46        switch (stringMap.get(1)) {
    47        default:
    48            System.out.println(&quot;Hello&quot;);
    49        }
    50
    51        String plainString = &quot;Test&quot;;
    52        switch (plainString) {
    53        default:
    54            System.out.println(&quot;Hi&quot;);
    55        }
    56    }
    57}
    58

    A sample run:

    1import java.util.HashMap;
    2import java.util.Map;
    3
    4public class SwitchFail {
    5  public static void main(String[] args) {
    6    //doesnt work
    7    Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    8    stringMap.put(1, &quot;Test&quot;);
    9    switch(stringMap.get(1)) {
    10    }
    11
    12    //works
    13    String plainString = &quot;Test&quot;;
    14     switch(plainString) {
    15    }
    16  }
    17}
    18Error: Unable to initialize main class SwitchFail
    19Caused by: java.lang.VerifyError: Bad type on operand stack
    20Exception Details:
    21  Location:
    22    SwitchFail.main([Ljava/lang/String;)V @33: invokevirtual
    23  Reason:
    24    Type 'java/lang/Object' (current frame, stack[0]) is not assignable to 'java/lang/String'
    25  Current Frame:
    26    bci: @33
    27    flags: { }
    28    locals: { '[Ljava/lang/String;', 'java/util/HashMap', 'java/lang/Object' }
    29    stack: { 'java/lang/Object' }
    30  Bytecode:
    31    0000000: bb00 1059 b700 124c 2b04 b800 1312 19b9
    32    0000010: 001b 0300 572b 04b8 0013 b900 2102 0059
    33    0000020: 4db6 0025 57b1  
    34
    35                   
    36            
    37List&lt;String&gt; stringList = Arrays.asList(&quot;Test&quot;);
    38switch(stringList.get(0)) {}
    39import java.util.HashMap;
    40import java.util.Map;
    41
    42public class SwitchFail {
    43    public static void main(String[] args) {
    44        Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    45        stringMap.put(1, &quot;Test&quot;);
    46        switch (stringMap.get(1)) {
    47        default:
    48            System.out.println(&quot;Hello&quot;);
    49        }
    50
    51        String plainString = &quot;Test&quot;;
    52        switch (plainString) {
    53        default:
    54            System.out.println(&quot;Hi&quot;);
    55        }
    56    }
    57}
    58[~/Desktop]: java SwitchFail.java
    59Hello
    60Hi
    61

    Test with jar:

    1import java.util.HashMap;
    2import java.util.Map;
    3
    4public class SwitchFail {
    5  public static void main(String[] args) {
    6    //doesnt work
    7    Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    8    stringMap.put(1, &quot;Test&quot;);
    9    switch(stringMap.get(1)) {
    10    }
    11
    12    //works
    13    String plainString = &quot;Test&quot;;
    14     switch(plainString) {
    15    }
    16  }
    17}
    18Error: Unable to initialize main class SwitchFail
    19Caused by: java.lang.VerifyError: Bad type on operand stack
    20Exception Details:
    21  Location:
    22    SwitchFail.main([Ljava/lang/String;)V @33: invokevirtual
    23  Reason:
    24    Type 'java/lang/Object' (current frame, stack[0]) is not assignable to 'java/lang/String'
    25  Current Frame:
    26    bci: @33
    27    flags: { }
    28    locals: { '[Ljava/lang/String;', 'java/util/HashMap', 'java/lang/Object' }
    29    stack: { 'java/lang/Object' }
    30  Bytecode:
    31    0000000: bb00 1059 b700 124c 2b04 b800 1312 19b9
    32    0000010: 001b 0300 572b 04b8 0013 b900 2102 0059
    33    0000020: 4db6 0025 57b1  
    34
    35                   
    36            
    37List&lt;String&gt; stringList = Arrays.asList(&quot;Test&quot;);
    38switch(stringList.get(0)) {}
    39import java.util.HashMap;
    40import java.util.Map;
    41
    42public class SwitchFail {
    43    public static void main(String[] args) {
    44        Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    45        stringMap.put(1, &quot;Test&quot;);
    46        switch (stringMap.get(1)) {
    47        default:
    48            System.out.println(&quot;Hello&quot;);
    49        }
    50
    51        String plainString = &quot;Test&quot;;
    52        switch (plainString) {
    53        default:
    54            System.out.println(&quot;Hi&quot;);
    55        }
    56    }
    57}
    58[~/Desktop]: java SwitchFail.java
    59Hello
    60Hi
    61[~/Desktop/java17]: javac SwitchFail.java 
    62[~/Desktop/java17]: jar -cvf java17test.jar .
    63added manifest
    64adding: SwitchFail.java(in = 379) (out= 212)(deflated 44%)
    65adding: SwitchFail.class(in = 920) (out= 546)(deflated 40%)
    66adding: .DS_Store(in = 6148) (out= 178)(deflated 97%)
    67[~/Desktop/java17]: java -cp java17test.jar SwitchFail
    68Hello
    69Hi
    70

    The JDK on my system:

    1import java.util.HashMap;
    2import java.util.Map;
    3
    4public class SwitchFail {
    5  public static void main(String[] args) {
    6    //doesnt work
    7    Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    8    stringMap.put(1, &quot;Test&quot;);
    9    switch(stringMap.get(1)) {
    10    }
    11
    12    //works
    13    String plainString = &quot;Test&quot;;
    14     switch(plainString) {
    15    }
    16  }
    17}
    18Error: Unable to initialize main class SwitchFail
    19Caused by: java.lang.VerifyError: Bad type on operand stack
    20Exception Details:
    21  Location:
    22    SwitchFail.main([Ljava/lang/String;)V @33: invokevirtual
    23  Reason:
    24    Type 'java/lang/Object' (current frame, stack[0]) is not assignable to 'java/lang/String'
    25  Current Frame:
    26    bci: @33
    27    flags: { }
    28    locals: { '[Ljava/lang/String;', 'java/util/HashMap', 'java/lang/Object' }
    29    stack: { 'java/lang/Object' }
    30  Bytecode:
    31    0000000: bb00 1059 b700 124c 2b04 b800 1312 19b9
    32    0000010: 001b 0300 572b 04b8 0013 b900 2102 0059
    33    0000020: 4db6 0025 57b1  
    34
    35                   
    36            
    37List&lt;String&gt; stringList = Arrays.asList(&quot;Test&quot;);
    38switch(stringList.get(0)) {}
    39import java.util.HashMap;
    40import java.util.Map;
    41
    42public class SwitchFail {
    43    public static void main(String[] args) {
    44        Map&lt;Integer, String&gt; stringMap = new HashMap&lt;&gt;();
    45        stringMap.put(1, &quot;Test&quot;);
    46        switch (stringMap.get(1)) {
    47        default:
    48            System.out.println(&quot;Hello&quot;);
    49        }
    50
    51        String plainString = &quot;Test&quot;;
    52        switch (plainString) {
    53        default:
    54            System.out.println(&quot;Hi&quot;);
    55        }
    56    }
    57}
    58[~/Desktop]: java SwitchFail.java
    59Hello
    60Hi
    61[~/Desktop/java17]: javac SwitchFail.java 
    62[~/Desktop/java17]: jar -cvf java17test.jar .
    63added manifest
    64adding: SwitchFail.java(in = 379) (out= 212)(deflated 44%)
    65adding: SwitchFail.class(in = 920) (out= 546)(deflated 40%)
    66adding: .DS_Store(in = 6148) (out= 178)(deflated 97%)
    67[~/Desktop/java17]: java -cp java17test.jar SwitchFail
    68Hello
    69Hi
    70[~/Desktop/java17]: java -version
    71openjdk version &quot;17&quot; 2021-09-14
    72OpenJDK Runtime Environment (build 17+35-2724)
    73OpenJDK 64-Bit Server VM (build 17+35-2724, mixed mode, sharing)
    74

    Source https://stackoverflow.com/questions/69197046

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