C / C++ / MFC

Maxwell Chen wrote:

You limit the maximal number of thread as 20, but in the while loop you test if(counter == 100) break;. The counter stops at value = 20. The loop can never break.

Evgeni57 wrote:

You are wrong. counter increased every time the thread created.

if(limit < maxNumberOfThreads)

const long MAXTHREADS = 100L;
const long MAXACTIVETHREADS = 20L;

int nThread = 0;
int nReleased = 0;
long lActiveThreads = 0L;
long lPreviousCount = 0L;

HANDLE hSemaphore = 0;
HANDLE hThread = 0;

const char *pSemaphoreName = "CreateThreadSemaphore";

bool Initialize()
{
	bool bResult = false;
	hSemaphore = ::CreateSemaphore(NULL, 0, MAXACTIVETHREADS, pSemaphoreName);
	bResult = (0 != hSemaphore);
	if (!bResult) {
		// TODO: report error from GetLastError()
	}

	return bResult;
}

DWORD WINAPI Start( LPVOID lpParam )
{
	// block til semaphore signals
	::WaitForSingleObject(hSemaphore, INFINITE);
	printf("End thread %d\n", GetCurrentThreadId());
	--lActiveThreads;

	++nReleased;
	::ReleaseSemaphore(hSemaphore, 1, &lPreviousCount);

	return TRUE;
}

void StartSimulation()
{
	while (nThread < MAXTHREADS) {
		if (lActiveThreads < MAXACTIVETHREADS) {
			DWORD dwThreadID = 0;
			hThread = ::CreateThread(NULL, 0, Start, NULL, 0, &dwThreadID); 
			if (!hThread) {
				// TODO: report error from GetLastError()
			} else {
				printf("Start thread %d\n", dwThreadID);
				::CloseHandle(hThread);	// throw away thread handle
				++lActiveThreads;
				++nThread;
			}
		} else {
			::ReleaseSemaphore(hSemaphore, 1, &lPreviousCount);
		}
	}

	// wait for all threads to end
	while (lActiveThreads) {
		::ReleaseSemaphore(hSemaphore, 1, &lPreviousCount);
	}

	// destroy hSemaphore
	::CloseHandle(hSemaphore);
	
	printf("Created %d threads.\n"
		"Release %d threads.\n"
		"PreviousCount %ld\n", nThread, nReleased, lPreviousCount);

}

int main()
{
	if (Initialize())
		StartSimulation();

	return 0;
}

narayanagvs wrote:

Any Suggestions or links would be appreciated