c - 为什么pthread会导致内存泄漏

Question

每当我创建 pthread 时，valgrind 都会输出内存泄漏，

例如下面的代码:

#include <stdio.h>
#include <unistd.h>
#include <pthread.h> 

void *timer1_function (void *eit){
  (void) eit;
    printf("hello world\n");
    pthread_exit(NULL);
}

int main(void){
   pthread_t timer1;
   pthread_create( &timer1, NULL, timer1_function,  NULL);  ///////line13
   int i=0;
   for(i=0;i<2;i++){usleep(1);}
   return 0;
}

valgrind 输出

==1395== HEAP SUMMARY:
==1395==     in use at exit: 136 bytes in 1 blocks
==1395==   total heap usage: 6 allocs, 5 frees, 1,134 bytes allocated
==1395== 
==1395== 136 bytes in 1 blocks are possibly lost in loss record 1 of 1
==1395==    at 0x402A629: calloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1395==    by 0x4011304: allocate_dtv (dl-tls.c:297)
==1395==    by 0x4011AAB: _dl_allocate_tls (dl-tls.c:461)
==1395==    by 0x4052470: pthread_create@@GLIBC_2.1 (allocatestack.c:571)
==1395==    by 0x8048566: main (test.c:13)
==1395== 
==1395== LEAK SUMMARY:
==1395==    definitely lost: 0 bytes in 0 blocks
==1395==    indirectly lost: 0 bytes in 0 blocks
==1395==      possibly lost: 136 bytes in 1 blocks
==1395==    still reachable: 0 bytes in 0 blocks
==1395==         suppressed: 0 bytes in 0 blocks

虽然我使用手册页作为引用，但为什么 pthread_create 会导致问题，我该如何解决？

Answer 1

线程是分配的资源，您在退出前没有释放它。您应该调用 pthread_join；这也将消除对您的骇人听闻和不正确的 sleep 循环的需要。

有可能即使你修复了这个问题，valgrind 仍然会看到“泄漏”，因为 POSIX 线程的一些实现(我猜你正在使用 glibc/NPTL)缓存并重用线程资源而不是完全释放它们.我不确定 valgrind 是否解决了这个问题。