分离的pthread和内存泄漏 [英] Detached pthreads and memory leak

问题描述

有人可以向我解释为什么这个简单的代码泄漏内存？

我相信，因为pthreads是创建分离状态，他们的资源应该在终止后立即释放，但不是这样。

我的环境是Qt5.2。

  #include< QCoreApplication> 
 #include< windows.h> 
 
 void * threadFunc（void * arg）
 {
 printf（＃）; 
 pthread_exit（NULL）; 
} 
 
 int main（）
 {
 pthread_t thread; 
 pthread_attr_t attr; 
 
 while（1）
 {
 printf（\\\
Starting threads ... \\\
）; 
 for（int idx = 0; idx< 100; idx ++）
 {
 pthread_attr_init（& attr）; 
 pthread_attr_setdetachstate（& attr，PTHREAD_CREATE_DETACHED）; 
 pthread_create（& thread，& attr，& threadFunc，NULL）; 
 pthread_attr_destroy（& attr）; 
} 
 printf（\\\
Sleeping 10 seconds ... \\\
）; 
 Sleep（10000）; 
} 
} 
  

UPDATE：

我发现如果我在中为循环增加了5毫秒的微小延迟，那么泄漏是 WAY 更慢： / p>



  for（int idx = 0; idx< 100; idx ++）
 {
 pthread_attr_init（& attr ）; 
 pthread_attr_setdetachstate（& attr，PTHREAD_CREATE_DETACHED）; 
 pthread_create（& thread，& attr，& threadFunc，NULL）; 
 pthread_attr_destroy（& attr）; 
 Sleep（5）; ///< --- 5 MILLISECONDS DELAY /// 
} 
  


这是让我失望，有人可以告诉我发生了什么？这种轻微的延迟会如何产生这样的重大变化？ （或以任何方式改变行为）

任何建议都将非常感激。

p>

UPDATE2：

在Windows平台（W7和XP）在Linux平台上没有观察到泄漏。（感谢@MichaelGoren）

解决方案

和内存消耗稳定。所以它必须是一个qt问题; cygwin上的pthread库工作正常，没有泄漏。

  #include< pthread.h> 
 #include< stdio.h> 
 #include< unistd.h> 
 
 
 void * threadFunc（void * arg）
 {
 printf（＃）; 
 pthread_exit（NULL）; 
} 
 
 int main（）
 {
 pthread_t thread; 
 pthread_attr_t attr; 
 int idx; 
 
 while（1）
 {
 printf（\\\
Starting threads ... \\\
）; 
 for（idx = 0; idx< 100; idx ++）
 {
 pthread_attr_init（& attr）; 
 pthread_attr_setdetachstate（& attr，PTHREAD_CREATE_DETACHED）; 
 pthread_create（& thread，& attr，& threadFunc，NULL）; 
 pthread_attr_destroy（& attr）; 
} 
 printf（\\\
Sleeping 10 seconds ... \\\
）; 
 // Sleep（10000）; 
 sleep（10） 
} 
} 
  

Can somebody please explain to me why this simple code leaks memory?

I believe that since pthreads are created with detached state their resources should be released inmediatly after it's termination, but it's not the case.

My environment is Qt5.2.

#include <QCoreApplication>
#include <windows.h>

void *threadFunc( void *arg )
    {
    printf("#");
    pthread_exit(NULL);
    }

int main()
    {
    pthread_t thread;
    pthread_attr_t attr;

    while(1)
        {
        printf("\nStarting threads...\n");
        for(int idx=0;idx<100;idx++)
            {
            pthread_attr_init(&attr);
            pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
            pthread_create( &thread, &attr, &threadFunc, NULL);
            pthread_attr_destroy ( &attr );
            }
        printf("\nSleeping 10 seconds...\n");
        Sleep(10000);
        }
    }

UPDATE:

I discovered that if I add a slight delay of 5 milliseconds inside the for loop the leak is WAY slower:

    for(int idx=0;idx<100;idx++)
        {
        pthread_attr_init(&attr);
        pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
        pthread_create( &thread, &attr, &threadFunc, NULL);
        pthread_attr_destroy ( &attr );
        Sleep(5); /// <--- 5 MILLISECONDS DELAY ///
        }

This is freaking me out, could somebody please tell me what is happening? How this slight delay may produce such a significant change? (or alter the behavior in any way)

Any advice would be greatly appreciated.

Thanks.

UPDATE2:

This leak was observed on Windows platforms (W7 and XP), no leak was observed on Linux platforms (thank you @MichaelGoren)

解决方案

I checked the program with slight modifications on windows using cygwin, and memory consumption was steady. So it must be a qt issue; the pthread library on cygwin works fine without leaking.

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


void *threadFunc( void *arg )
{
printf("#");
pthread_exit(NULL);
}

int main()
{
pthread_t thread;
pthread_attr_t attr;
int idx;

while(1)
    {
    printf("\nStarting threads...\n");
    for(idx=0;idx<100;idx++)
        {
        pthread_attr_init(&attr);
        pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
        pthread_create( &thread, &attr, &threadFunc, NULL);
        pthread_attr_destroy ( &attr );
        }
    printf("\nSleeping 10 seconds...\n");
    //Sleep(10000);
sleep(10);
    }
}

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