pthreadExample.cpp

// Basic thread performance test
// Two threads alternate incrementing a counter up to a limit.
// On my Mac (2.6 GHz Intel Core i7) the average time per loop
// iteration (with a lock and an unlock) is 44 ns.
// So to keep lock overhead small, do no more than a million/sec.

#include "Misc.h"

int lockCount = 0;
pthread_mutex_t clok;

using namespace forest;

void* f(void* start) {
                int i = *((int *) start);
                while (i < 10000000) {
                                pthread_mutex_lock(&clok);
                                if (lockCount != i) { pthread_mutex_unlock(&clok); continue; }
                                lockCount++; i += 2;
                                pthread_mutex_unlock(&clok);
                }
}

int zero = 0;
int one = 1;

int main() {
                int startTime = Misc::getTime();

                pthread_t t0, t1;
                pthread_create(&t0,NULL,f,(void *) &zero);
                pthread_create(&t1,NULL,f,(void *) &one);

                pthread_join(t0,NULL); pthread_join(t1,NULL);
                cout << Misc::getTime() - startTime << endl;
}