How to simulate “out of memory issue” in Linux

Question

I want to reproduce one issue, pre-requisite is setting system "Out of memory" then check how a process behaves.

without affecting the other users, i have to simulate this issue, since so many other users using Linux machine in parallel.

Answer 1

You can set the memory available to a process by using ulimit .

Here is how you would do that in a console:

ulimit -v 64 -m 64
./program # Run the program you want to test. 

Example

Here is an example which I tested on Ubuntu 14.04. It did not work on macOS High Sierra! On Ubuntu/Linux it works fine.

// Compile with 'clang++ <filename>' or the compiler of your choice
#include <iostream>
#include <cstdlib>

int main(int argc, char** argv) {
    if (argc != 2) return 1;
    std::size_t size = std::atoi(argv[1]);
    const void* ptr = std::malloc(size);

    const std::string result = ptr ? "worked" : "failed";
    std::cout << "Allocating " << size << " bytes " << result << "." << std::endl;
}

On command line:

❯ ./a.out 100000000000000000
Allocating 1569325056 bytes worked.
❯ ulimit -v 100000 -m 100000 . # Before these values were at 'unlimited'
❯ ./a.out 100000000000000000
Allocating 1569325056 bytes failed.

Answer 2

If it's not too much of an overhead, you could probably run your process in a Docker container and set a memory limit. Docker would isolate your process from other parts of the system, and you can set a memory limit, too. See here about configuring a container's resources in Docker.

I think the other answer is better though, but Docker would help you minimize the impact on other users if that could be an issue.