(OpenMP, C++ME, System.Threading.Thread) -> Resource Leak.

Here is the source code of my C++/ME app. When I run it I can use "Windows Task Manager" to see that thread HANDLEs are leaking.

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#include "stdafx.h"

#include <omp.h>
 
public __gc class TestClass

{

public:

    void ThreadProc()

    {

        int sum = 0;
 
#pragma omp parallel for reduction(+:sum)

        for ( int i = 0; i < 10000; i++ )

        {

            sum += i;

        }
 
        System::Console::WriteLine( sum.ToString() );

    }

};
 
int main()

{

    for (;;)

    {

        TestClass __gc * o = __gc new TestClass();

        System::Threading::Thread __gc * t = __gc new System::Threading::Thread( 

                    __gc new System::Threading::ThreadStart( o, &TestClass::ThreadProc ) );
 
        t->Start();
 
        System::Threading::Thread::get_CurrentThread()->Sleep( 100 );

    }

}

If I put something that is not using Open MP into the ThreadProc no HANDLEs will be leaked.
I realize that what happens is: Omp creates unmanaged threads inside a managed thread (i.e. System::Threading::Thread). I just have very little idea about what could be wrong with it. If somebody will try to reproduce this, I am currently using VS2005.
Thanks for all your comments and suggestions.

Oct 1 '07 #1

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2476

gnanapoongothai

I think i have got ur problem. there are unmanaged threads when using openmp.is it so?

openmp architecture is like when u specify the openmp pragma, it creates a new thread for ur loop and once finished joins the main thread.this might be ur problem. I am not versatile in openmp. But this is a new concept only less ppl use it.so keep in touch to discuss about openmp

Oct 5 '07 #2

PimpDaddy

We recently discovered that the thread leak has nothing to do with .NET. The same leak occurs even if we run OpenMP code inside a Win32 thread. So, here is the new example. Suggestions\ideas, please?

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#include <windows.h>

#include <stdio.h>

#include <omp.h>
 
int calculateArithmeticalProgressionSumOMP( int a1, int d, int n )

{

    int sum = 0;

    omp_set_num_threads(3);

#pragma omp parallel 

    {

#pragma omp for reduction (+: sum)

        for( int i = 0; i < n; i++)

        {

            int a = a1 + i * d;

            sum += a;                                                                                                                                                                                      

        }

    }

    return sum;

}
 
DWORD threadFunc(LPVOID pParams)

{

    int sum = calculateArithmeticalProgressionSumOMP(0, 1, 10000);

    printf("%d\n", sum);

    return 0;

}
 
int main()

{

    //create some threads

    for(int i = 0; i < 100; i++)

    {

        HANDLE handle;

        handle = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE )threadFunc, NULL, 0, NULL);

        WaitForSingleObject(handle, INFINITE);

        Sleep(100); //imitating some other work

    }
 
    return 0;

}

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(OpenMP, C++ME, System.Threading.Thread) -> Resource Leak.

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