how to implement WaitForMultipleObjects in linux

shamjs · 10-17-2011, 05:31 AM

Hi,All
for synchronization of threads im using WaitForMultipleObjects in windows,but my questions is how to do the same in linux since there is no equivalent api in linux.....
Here is my code

Code:

long PredictThread(const Array2D<REAL> &X)  //For generating members matrix only
	{
		if (X.dim2()!=m_NumVars) return -1;
		long i,j;
		
		Array3D<REAL>  Ypred(X.dim1(),m_Categories.size(), 6, 0.0);
			
		HANDLE* TID = new HANDLE[m_Categories.size()];
		DWORD ThreadID;

		TParam* pOTParam = new TParam[m_Categories.size()];
		TParam* pTParam = pOTParam;
		for(j=0;j<m_Categories.size();++j)
		{
			TParam* pParam = pTParam;
			pParam->category = j;
			pParam->model = m_Categories[j];
			pParam->X = X.copy();
			pParam->Ypred = Ypred;

			TID[j] = CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)ThreadProc,(LPVOID)pParam,0,&ThreadID);
			pTParam++;
		}
		WaitForMultipleObjects(m_Categories.size(), TID, TRUE, INFINITE);
		for(j=0;j<m_Categories.size();++j)
			CloseHandle(TID[j]);

		delete [] TID;
		delete [] pOTParam;
		m_members = Ypred;		
		return 0;
	}

please suggest me to do this
thannx.................

lior.okman · 10-18-2011, 01:45 AM

Quote:

Originally Posted by shamjs

Hi,All
for synchronization of threads im using WaitForMultipleObjects in windows,but my questions is how to do the same in linux since there is no equivalent api in linux.....

You can use a semaphore to do this. For example, consider the following program:

Code:

#include <stdlib.h>
#include <stdio.h>
#include <semaphore.h>
#include <pthread.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

#define NUM_THREADS (2)

sem_t semaphore;

void *worker_thread(void *arg) 
{
	int i;
	for (i=0; i<10; ++i) {
		fprintf(stderr,".");
		sleep(1);
	}
	sem_post(&semaphore);
	return NULL;
}


int main(int argc, char* argv[])
{
	pthread_t thread[NUM_THREADS];
        int i;
	sem_init(&semaphore, 0, -1 * NUM_THREADS);

        for (i =0; i< NUM_THREADS; ++i) {
                 pthread_create(&thread[i],NULL, &worker_thread, NULL);
        }

	if (sem_wait(&semaphore) < 0) {
		printf("sem_wait failed: %s\n", strerror(errno));
		return EXIT_FAILURE;
	}
        for (i =0; i< NUM_THREADS; ++i) {
	       pthread_join(thread[i], NULL);
        }
        printf("\nAll threads are done now\n");
	return EXIT_SUCCESS;
}