Detached pthreads and memory leak

Question

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)

Answer 1

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);
    }
}