jmap | A Java 8 library for the JSON Meta Application Protocol | JSON Processing library
kandi X-RAY | jmap Summary
kandi X-RAY | jmap Summary
A library to synchronize data between a client and a server using the JSON Meta Application Protocol. The current focus is on acting as a client library to retrieve emails from a server however it is easily extensible to also synchronize contacts and calendars. It might even be extended to act as a server library. The library is written in Java 8 to provide full compatibility with Android. It uses GSON for JSON serialization and deserialization and makes heavy use of Guava including its Futures. Entities (Mailbox, Email, EmailSubmission, …) and method calls are annotated with Project Lombok’s @Getter and @Builder to make them immutable.
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Top functions reviewed by kandi - BETA
- Resolves the thread ids
- Called by the synchronized methods
- Completes changes to send changes
- Calculate change state response
- Handles getMail method response
- Handles push subscription call
- Resolves the email
- Execute set mailbox response
- Determines if a method call is sent
- Handles send email
- Create a type adapter for the given type token
- Loads the entity to filter condition map
- Creates a bi - map for the given type
- Serialize an Invocation
- Parse the given body into a list of Block objects
- Returns the object that represents the query result
- Performs an initial query
- Gets the namespaces declared in the given method call
- Process Jmap capabilities
- Add a query result to the cache
- Serialize a single message
- Process Jmap AccountCapability
- Deserialize a JSON message
- Decode a JSON document to retrieve a result reference
- Dispatch method calls
- Registers the given GsonBuilder
- Process create email method
- Deserialize an invocation
- This method processes the given round environment
jmap Key Features
jmap Examples and Code Snippets
Lines of Code : 51License : Permissive (Apache-2.0)
Copyimplementation 'rs.ltt.jmap:jmap-client:0.7.4'
rs.ltt.jmap
jmap-client
0.7.4
JmapClient client = new JmapClient("user@example.com", "password");
Session session = client.getSession().get();
String accountId = session.getPrimaryAccount(Mail implementation 'rs.ltt.jmap:jmap-mua:0.7.4'
rs.ltt.jmap
jmap-mua
0.7.4
Community Discussions
Trending Discussions on jmap
QUESTION
I have the following Swift code with some sample JSON that I'm trying to decode. You can drop this into a Playground to try it for yourself:
...ANSWER
Answered 2022-Mar-06 at 07:23Your JMAPResponseChild is decoding an array expecting either a String or JMAPMethodResponse. The array looks like this:
QUESTION
We all know good old flag +HeapDumpOnOutOfMemoryError for taking heap dumps when JVM runs out of memory. Problem with this is that for large heaps this takes more and more time.
There is a way to take fast heap dumps using GNU Debugger...
You effectively take the core file of the process (very fast) then convert it to heapdump format using jmap... this is the slowest part of the work.
However this is only if you take it manually, when your java apps run in containers there is usually a fixed timeout until your app will be killed non gracefully... for kube i believe it is 30 seconds by default.
For many reasons i do not want to extend this timeout to larger number. Is there a way to trigger only core file dump when out of java runs out of memory? or we are just limited with whatever +HeapDumpOnOutOfMemoryError flag offers?
ANSWER
Answered 2022-Jan-21 at 17:58I can think of 2 possible solutions but it wont be only for out of memory situations but crashes too:
You can use java's
-XX:OnErroroption to run your own script or gcore, (gdb) generate-core-file(depends to your OS) to create an core dump that you can later use a debugger(like gdb) to attach to it.You can enable auto core dumps in your OS in the way it provides. For Redhat:
To enable: Edit the related line in file /etc/systemd/system.conf as DefaultLimitCORE=infinity
Reboot and remove the limits of core dump by ulimit -c unlimited.
When your application crashes, the dumb must be created in its working directory.
QUESTION
I'm running my java application on apline linux system in docker container, and I wanna find out the value of MaxHeapSize, so I use several command : java -XX:+PrintFlagsFinal, jinfo -flag MaxHeapSize , jmap -heap, but the output made me feel confused. The output of jinfo -flag MaxHeapSize , jmap -heap are consistent. However, The output of java -XX:+PrintFlagsFinal is different.so why did this happen?
The default container memory Limit setting is 4096MiB.
The output of java commonds is shown below.(I marked some important parts in the picture)
...ANSWER
Answered 2022-Jan-14 at 05:10These are not comparing the same thing.
When running jmap or jstack, these attach to the existing process with PID 9, as listed in the first jps command.
When running java -XX:+PrintFlagsFinal -version, this creates a new JVM process, and prints the information for that new process. Note that the original PID 9 process has a number of additional flags that can affect the calculated heap size.
For a more accurate comparison, you could add the -XX:+PrintFlagsFinal flags to the main command run when the container starts. I would expect this to match the values returned by jinfo and jmap.
QUESTION
jmap -histo {pid} shows the following result:
ANSWER
Answered 2021-Nov-30 at 02:47As @boneill points out, under the hood jmap -histo:live performs a full GC ... to determine what objects are live. And jmap -histo ... doesn't.
Why my JVM has so many old char and string?
Is this normal or do I need to concern?
It is hard to say. There is insufficient evidence.
But, without other evidence, I'd say "not concerning".
where are the other 860M Chars?
First of all [C doesn't mean Char. It means char[].
Where are they? Well my reading is that they are unreachable. (Not live). They are candidates for garbage collection.
... and why they aren't be GC?
Because the GC hasn't collected them yet.
Java garbage collection is ... complicated. Many of the collectors are generational meaning that they split the heap into new and old object spaces. The new space is collected frequently. The old space is collected infrequently. So if most of those objects have been tenured to the old space, they may life a relatively long time after they have become unreachable.
That is one possible explanation.
When will these Chars be GC?
When the old space is collected. Probably.
How can I make them immediately GC to save memory?
You could call System.gc() to ask the JVM to run a (typically) full garbage collection. But ...
- the JVM may ignore that request entirely,
- it might not run a full GC (that's possibly implementation dependent),
- even if the objects are collected, you most likely won't save any actual memory.
Why don't you save memory? Because the JVM hangs on to the free space it got back ... ready to allocate new objects. So the memory is not returned to the OS for other applications to use. (There is some complicated logic for heap resizing, but as a rule the JVM gives back memory reluctantly; i.e. only after a number of full GC cycles.)
Finally, calling System.gc() in your application code is bad for performance ... in most circumstances. There are other Q&As that explain why.
QUESTION
I'm able to use jmap command to dump JVM memory heap.
The issue is, I have a program with heavier young gen GC activities compared to the previous version when checking from the GC logs, and when I ran memory profiler, the biggest objects are always the ones in the old gen. So it makes troubleshooting more difficult when you need to find the leaks that exist in young gen GC.
Is there any way to profile the memory in the young gen heap?
Updated: I used open JDK 1.8.
...ANSWER
Answered 2021-Nov-28 at 11:00The profiling interface of the JVM does not provide GC-specific information, so profilers cannot tell you what GC generation an object is in.
However, some profilers have the ability to record how old an object is (effectively making their own "generations") so you can restrict your analysis to younger objects only. JProfiler, for example has a "Set mark" action that marks all objects in the heap.
After you create a heap dump, you can select objects that have been created after the mark action was invoked.
If you choose to record allocation times, you can select objects created in arbitrary time intervals in the "Time" view of the heap walker.
Disclaimer: My company develops JProfiler
QUESTION
I've Linux Mint 20.2 Cinnamon and I tried to install jenkins. Detailed steps for installation is as below:
1. Installing java - installed via apt
ANSWER
Answered 2021-Nov-26 at 06:56jenkins will work with java 8 on mint 20 and 21. If you have different java versions installed on your system then select the jdk8 as default by
QUESTION
I have more than one java application running in separate docker containers. I am trying to collect monitoring data such as GC log, thread dump, heap dump from the java process running inside a container using tools like jstat, jstack, jmap. Is it possible to capture this information from the host(outside containers)?
I am new to the containerized world. I understand that PID namespace of the host and container is different. When I execute jstack > thread_dump.txt from the host, it shows error message: Unable to open socket file /proc/root/tmp/.java_pid: target process doesn't respond within 10500ms or HotSpot VM not loaded
Where PID is process id from the host PID namespace.
When I execute jstack inside container ( docker exec -it ) then it is able to capture thread dump.
Where PID is process id from the container PID namespace.
Any hints on how to solve this?
...ANSWER
Answered 2021-Aug-31 at 13:17The command you should use is:
QUESTION
I am running Tomcat 9 on an Ubuntu 20.04 OS using OpenJDK 64-Bit Server VM (build 25.275-b01, mixed mode). When I try to gather diagnostics info using jstat, jstack, etc, I see PID not found. jps also cannot identify the Tomcat process id.
I have checked several posts like one, two, three, four, etc, but none of the answers given in these helped me to solve my problem!
Even though I am passing the username with which the Tomcat process is running, jstat cannot find that process: sudo -u tomcat jstat -gc 476174 5000
In case it matters:
- I can see that the Tomcat process is started with
-Djava.io.tmpdir=/tmpThis folder is owned by root user but has full permissions(777) enabled. - When the Tomcat process is started, I can see a folder with name
systemd-private-e6d8b5dc224848f8a64a3e943ac2e9c4-tomcat9.service-UH5knj(the last few chars after service- change every time the process is restarted) getting created with owner as root (probably because I start tomcat service usingsudo service tomcat9 start) and this folder has permission ofrwx------.
Any hints on how to solve this issue?
Thanks, Shobhana
...ANSWER
Answered 2021-Feb-09 at 20:58All these tools (jstack, jmap, jstat...) rely on the communication with the target JVM through /tmp directory.
Apparently Tomcat runs in a different mount namespace, so that its /tmp directory is not the same as /tmp of the current shell. To verify this, run
QUESTION
I'm trying to send events from my mobile application to Google analytics.
External library connected:
com-google-android-gms.play-services-analytics-impl.16.0.8.jar
Androidapi.JNI.PlayServices
After launching the application, I get the following.
...ANSWER
Answered 2021-Apr-23 at 13:32After digging around in the documentation. GoogleAnalytics I found this.
This code is used for universal analytics not GA4 so if you are trying to use this to send data to GA4 its not going to work.
QUESTION
when we execute jmap -heap pid , the target java process can't handle any http request.
env ...ANSWER
Answered 2021-May-27 at 00:37we had received some warning about ECS from aliyun once, so we upgraded some patch.
from that, we found some software that be influenced, like glibc, then we upgrade glibc and jmap worked
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
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Install jmap
You can use jmap like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the jmap component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer maven.apache.org. For Gradle installation, please refer gradle.org .
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