Home/ Questions/Q 6029381
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-23T04:52:40+00:00

I have a simple program which creates a thread, and waits when this thread

  • 0

I have a simple program which creates a thread, and waits when this thread ends, and then the program also ends. When I compile this program with C(gcc) compiler, and check it with valgrind, no problem is occured, but when I compile it with C++(g++) compiler, and check with valgrind, it shows that my program has memory leaks. What could be the problem?

Here is my program,

#include <pthread.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>


unsigned char b = 0;


void* threadfunc1( void *pVoid )
{
    while( b == 0 )
    {
    usleep(10000);
    }
    pthread_exit(0);
}



int main(void)
{

    int status;
    pthread_attr_t tattr;
    pthread_t   thread1;

    status = pthread_attr_init(&tattr);
    status = pthread_attr_setdetachstate(&tattr,PTHREAD_CREATE_JOINABLE);
    status = pthread_attr_setscope(&tattr,PTHREAD_SCOPE_SYSTEM);

    if( pthread_create( &thread1, &tattr, threadfunc1, NULL ) != 0 )
    {
        exit(1);
    }

    usleep(1000000);
    b = 1;
    pthread_join( thread1, NULL);
    usleep(2000000);

    return 0;
}

this is the result, when I compile it using g++, and check in valgrind

==7658== HEAP SUMMARY:
==7658==     in use at exit: 28 bytes in 1 blocks
==7658==   total heap usage: 2 allocs, 1 frees, 172 bytes allocated
==7658== 
==7658== 28 bytes in 1 blocks are still reachable in loss record 1 of 1
==7658==    at 0x4024C1C: malloc (vg_replace_malloc.c:195)
==7658==    by 0x400C01E: _dl_map_object_deps (dl-deps.c:506)
==7658==    by 0x40117E0: dl_open_worker (dl-open.c:297)
==7658==    by 0x400D485: _dl_catch_error (dl-error.c:178)
==7658==    by 0x401119F: _dl_open (dl-open.c:586)
==7658==    by 0x428D0C1: do_dlopen (dl-libc.c:86)
==7658==    by 0x400D485: _dl_catch_error (dl-error.c:178)
==7658==    by 0x428D1C0: dlerror_run (dl-libc.c:47)
==7658==    by 0x428D2DA: __libc_dlopen_mode (dl-libc.c:160)
==7658==    by 0x4048876: pthread_cancel_init (unwind-forcedunwind.c:53)
==7658==    by 0x40489EC: _Unwind_ForcedUnwind (unwind-forcedunwind.c:126)
==7658==    by 0x40464B7: __pthread_unwind (unwind.c:130)
==7658== 
==7658== LEAK SUMMARY:
==7658==    definitely lost: 0 bytes in 0 blocks
==7658==    indirectly lost: 0 bytes in 0 blocks
==7658==      possibly lost: 0 bytes in 0 blocks
==7658==    still reachable: 28 bytes in 1 blocks
==7658==         suppressed: 0 bytes in 0 blocks

So, what I’m doing wrong, is it my error or …, why when I compile it with gcc no problems are occured and when I compile it using C++ memory leaks are present?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Your program don’t have memory leaks, you have

    ==7658==    definitely lost: 0 bytes in 0 blocks
==7658==    indirectly lost: 0 bytes in 0 blocks
==7658==      possibly lost: 0 bytes in 0 blocks

    “still reachable” does not mean memory leak.

    There are much questions here about “still reachable” by valgrind. Some of them:

    • 0