Problem in mutex?

[Shachar Shemesh]

Hi all,
Attached is a sample program, originally written to find out about the 
impact of using epoll on performance.

However, the program doesn't run properly. When running it, I get 
deadlocked.

Does anyone have any explanation? Is it a bug in my Win32 code?
err:ntdll:RtlpWaitForCriticalSection section 0x4017fec0 "?" wait timed 
out in thread 0009, blocked by 0000, retrying (60 sec)

         Shachar
--
Shachar Shemesh
Lingnu Open Source Consulting ltd.
http://www.lingnu.com/
#include <windows.h>
#include <stdio.h>
#define NUMTHREADS 3000

int flag;
int count;

DWORD WINAPI ThreadMain( LPVOID lpParam )
{
    HANDLE hmutex=CreateMutex( NULL, FALSE, "ThreadCreationTest");
    int i=0;

    for( i=0; i<100; ++i )
    {
        DWORD dwWait=WaitForSingleObject(hmutex,INFINITE);
        switch( dwWait ) {
        case WAIT_OBJECT_0:
            {
                int oldcount=count;
                if( flag )
                    fprintf(stderr, "No mutual exclusion!\n");
                flag=1;
                oldcount++;
                count=oldcount;
                flag=0;
            }
            ReleaseMutex(hmutex);
            break;
        default:
            fprintf(stderr, "Didn't get mutex %lx\n", dwWait );
            break;
        }
    }
    
    CloseHandle(hmutex);

    printf("Thread %d exiting with count at %d\n", lpParam, count );

    return 0;
}

int main( int argc, char *argv )
{
    int i;
    HANDLE threads[NUMTHREADS];
    
    flag=0;
    count=0;

    for( i=0; i<NUMTHREADS; ++i ){
        DWORD threadid;
        threads[i]=CreateThread(NULL, 0, ThreadMain, (LPVOID)i, 0, &threadid);
        if( threads[i]==NULL)
            fprintf(stderr, "Failed to create thread %lx\n", GetLastError() );
    }

    WaitForMultipleObjects(NUMTHREADS, threads, TRUE, INFINITE);

    fprintf(stderr,"Program exit %d\n", count);

    return 0;
}