nalloc | Off-heap memory allocators for Java
kandi X-RAY | nalloc Summary
kandi X-RAY | nalloc Summary
Nalloc contains factories for allocating Java objects from native heap and memory mapped files. Basically void* and mmap in Java. Off-heap storage is usually required with huge datasets (eg. caches and data grids) or with systems with hard latency requirements (eg. stock trading). Instantiating tens of millions of data entries from JVM heap is slow and likely to cause GC trashing. Off-heap storage for N entries can be instantiated in O(1) and data can be handled in pre-allocated arrays with direct pointer access. Nalloc uses almost no JVM heap once initialized and is suitable for systems requiring "garbage free" design.
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Top functions reviewed by kandi - BETA
- Maps a file to an array of bytes
- Maps a ByteBuffer to a mapped byte buffer
- Creates a mapped memory buffer of the specified type
- Allocates memory to a given array
- Address
- Allocates memory allocated to the given number of bytes
- Creates a native struct instance
- Utility method to read an ASCII string
- Returns a copy of a byte array
- Sets the characters in the specified array
- Sets an array of integers
- Sets the long at the given address
- Sets longs in the buffer
- Retrieves the int value at the given address
- Clears the value at the given index
- Stores an int at the given address
- Returns a char array containing the specified length bytes
- Allocates memory for a given type
- Retrieves a string from the given address
- Sets the chars in the given array of bytes
- Retrieves a long array of the specified length
- Writes a string in an ASCII string
- Returns an array of unicode character chars
- Retrieve an array of ints from the given address
nalloc Key Features
nalloc Examples and Code Snippets
Lines of Code : 54License : Permissive (Apache-2.0)
Copy@Struct({
@Field(name="id", type=Type.LONG)
@Field(name="type", type=Type.String, len=10) })
public interface Message {
long id();
void id(long id);
String name();
void name(String name);
}
@Struct({
@Field(name="hist MmapAllocator allocator = MmapAllocator.Factory.create(MyStruct.class);
Array messages = allocator.mmap(new File("/tmp/my-index"), 1000000, MyStruct.class);
// write to array index 5000
MyStruct my = messages.get(5000);
my.myAge('X');
ByteBuffer buf NativeHeapAllocator allocator = NativeHeapAllocator.Factory.create(Message.class);
Pointer ptr = allocator.malloc(Message.class);
Message message = ptr.deref();
message.content("Hello world!");
System.out.println(message.content());
ptr.free();
Community Discussions
Trending Discussions on nalloc
QUESTION
So, I tried to run my go code on C++ project with dynamic loading. It's working great, except there is some unwanted string on returned value. As I explained down, I got some information from Go that unwanted.
My go code:
...ANSWER
Answered 2021-Dec-09 at 08:19When passing strings via pointer to C you need either use length (n) in GoString to fetch right number of characters as string at p is not \0 terminated. Or you can return *C.char instead of string and use C.CString() to allocate copy on C heap (which you then are responsible for freeing after use). See Cgo documentation here.
What is happening in your code is that printf() simply prints all characters starting from location pointed to by string.p until it hits \0 terminator - that's why you see contents of memory after test.
So you can do either something like:
QUESTION
I am currently implementing my own pool allocator to store n chunks of the same size in one big block of memory. I am linking all the chunks together using a *next pointer stored in the struct chunk like this
ANSWER
Answered 2021-Dec-04 at 22:33When you add to pointers, pointer arithmetic is used. With pointer arithmetic, the memory address result depends on the size of the pointer being added to.
Let's break down this expression:
QUESTION
I am building a Docker image with python 3.7.10 (Linux Alpine v3.13) but when building the image with docker build . the package hdf5 will fail during the installation. This is my Dockerfile:
ANSWER
Answered 2021-Mar-19 at 16:16Seems like I have used a wrong and old h5py version (h5py==2.10.0). The following setup worked just fine when updating to h5py==3.2.1 within the requirements.txt.
QUESTION
#include
int main() {
char *mystring = calloc(2, sizeof(char));
scanf("%10[^\n]s", mystring);
printf("\nValue: %s\nSize of array: %d\nAllocated space: %d\n",
mystring, 2 * sizeof(char), sizeof(char) * strlen(mystring));
free(mystring);
}
ANSWER
Answered 2020-May-18 at 19:57Option #1
from Kernighan and Ritchie 2nd ed appendix B.1.4
QUESTION
Much thanks for the help in additionally. I'm trying to build a BVH Tree with Surface Area Heuristic, but everytime I compile my code it gives me random errors like:
"Access violation reading location"
"Run-Time Check Failure #2 - Stack around the variable 'x' was corrupted."
"Stack overflow "
The errors happen in the BVH::buildSAH() function. And I have tried to find a solution for the whole day, meaningless. Could it be something from the std::partition function or from sending variables with pointers to a recursion?
I'm reading from the book "Physically Based Rendering: From Theory to Implementation By Matt Pharr, Greg Humphreys"
It works for 2 primitives in the area, but thats trivial... If you would like to clone: https://github.com/vkaytsanov/MortonCode-BVH-KD My BVH.hpp:
...ANSWER
Answered 2020-Apr-06 at 20:18Probably it would be wise to first cleanup your github. This mean update stuff to the recent c++ standard. It seems that you can use c++17 so use it. Also please look at some names. For example 'nodes' is used as member variable as well as parameter name, this is confusion. Please also initialize relevant (all) member variables.
Now it seems that the code in buildSAH override memory. It seems that it it can write over the end of buckets array.
QUESTION
#include
#include
#include
#include
int main() {
int i = 0;
struct rusage r_usage;
while (++i <= 10) {
void *m = malloc(20*1024*1024);
memset(m,0,20*1024*1024);
getrusage(RUSAGE_SELF,&r_usage);
printf("Memory usage = %ld\n",r_usage.ru_maxrss);
sleep (3);
}
printf("\nAllocated memory, sleeping ten seconds after which we will check again...\n\n");
sleep (10);
getrusage(RUSAGE_SELF,&r_usage);
printf("Memory usage = %ld\n",r_usage.ru_maxrss);
return 0;
}
ANSWER
Answered 2020-Mar-20 at 18:18Resident set size (RSS) means, roughly, the total amount of physical memory assigned to a process at a given point in time. It does not count pages that have been swapped out, or that are mapped from a file but not currently loaded into physical memory.
"Maximum RSS" means the maximum of the RSS since the process's birth, i.e. the largest it has ever been. So this number tells you the largest amount of physical memory your process has ever been using at any one instant.
It can vary from one run to the next if, for instance, the OS decided to swap out different amounts of your program's memory at different times. This decision would depend in part on what the rest of the system is doing, and where else physical memory is needed.
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