Reputation: 85

posix timer_create() function causing memory leak on linux

I am using timer_create function for timer functionality in my application. When timeout happens, a new thread gets created. That time my application's memory usage is getting increased by around 11mb. I also have set the thread attribute to PTHREAD_CREATE_DETACHED. Any help is appreciated. I also want to know how long will the thread that gets created when timeout happens be alive?

Minimal reproducible example:

#include <csignal>
#include <ctime>

int main(){
    struct sigevent signalEvent;
    signalEvent.sigev_notify = SIGEV_THREAD;
    signalEvent.sigev_notify_function = [](sigval_t){};
    signalEvent.sigev_notify_attributes = nullptr;
    void* timerId = nullptr;
    timer_create(CLOCK_REALTIME, &signalEvent, &timerId);
    return 0;
}

Running this with g++ main.cpp && valgrind ./a.out gives:

==4007020== LEAK SUMMARY:
==4007020==    definitely lost: 0 bytes in 0 blocks
==4007020==    indirectly lost: 0 bytes in 0 blocks
==4007020==      possibly lost: 272 bytes in 1 blocks
==4007020==    still reachable: 88 bytes in 1 blocks
==4007020==         suppressed: 0 bytes in 0 blocks

Upvotes: 1

Answers (5)

ch0kee

Reputation: 746

Too few info given, but maybe helps:
Periodic Timer Overrun and Resource Allocation

Upvotes: 0

Nils Pipenbrinck

Reputation: 86353

I doubt it has anything to do with your timer.

If you create a new thread, the thread needs space for the stack. As far as I know this memory gets allocated once at thread creation because it has to be contiguous.

That may sound like a lot of wasted memory, but it is not. First off, you can lower the stack size if you want, second: Only the address-space inside your process gets allocated. Physical memory only gets allocated if you use the stack.

Upvotes: 1

user3458

Reputation:

Any thread stays "active" until you exit its thread function. Your leak is most probably the thread's stack - that will not go away until you invoke thread_join or some such.

Upvotes: 0