I have a program with several threads, one thread will change a global when it exits itself and the other thread will repeatedly poll the global. No any protection on the globals. The program works fine on uni-processor. On dual core machine, it works for a while and then halt either on Sleep(0) or SuspendThread(). Would anyone be able to help me out on this?

The code would be like this:

Thread 1:

do something...
while(1)
{
.....
flag_thread1_running=false;
SuspendThread(GetCurrentThread());
continue;

}

Thread 2
....
while(flag_thread1_running==false) Sleep(0);
....