thread.c file:
#include <pthread.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <math.h>
#define THREADS_COUNT 7
#define NITER 10000000
int count = 0;
sem_t mutex;
int threads_count = THREADS_COUNT;
int iterations_count = NITER;
pthread_t thread_first_id;
short thread_first_started = 0;
void *thread_function(void *data)
{
int i, tmp;
int processed_count = 0;
pid_t pid = getpid();
int *id = data;
pthread_t self = pthread_self();
long thread_id = (long) self;
printf("process %ld, thread %ld entering. id=%d\n", pid, thread_id, *id);
if (thread_id == thread_first_id) {
thread_first_started = 1;
printf("Thead 1 started. Sleeping. id=%d\n", *id);
usleep(2000);
printf("Thead 1 started. Awaking. id=%d\n", *id);
}
else {
while (!thread_first_started) {
printf("process %ld, thread %ld waiting.\n", pid, thread_id);
usleep(100);
}
}
while (count < NITER) {
sem_wait(&mutex);
++count;
if (count > iterations_count) {
sem_post(&mutex);
break;
}
double x = pow(i, i);
double s = sqrt(x);
double c = cbrt(x);
double l = log(x);
double l10 = log10(x);
double e = exp(x);
++processed_count;
//printf("%ld - %d\n", thread_id, count);
sem_post(&mutex);
}
printf("process %ld, thread %ld exiting. Processed items = %d, %.2f%% of total.\n",
pid,
thread_id,
processed_count,
100.0 * processed_count / (double) iterations_count);
pthread_exit(NULL);
}
int main(int argc, char *argv[])
{
if (argc > 1) {
iterations_count = atoi(argv[1]);
}
if (argc > 2) {
threads_count = atoi(argv[2]);
}
printf("iterations = %d\n", iterations_count);
printf("threads = %d\n", threads_count);
pthread_t threads[threads_count];
int i;
int *data;
// Initializing unamed semaphore
sem_init(&mutex, 0, 1);
// Starting threads
for (i = 0; i < threads_count; i++) {
data = (int *) malloc(sizeof(int));
*data = i;
printf("Creating thread %d with data=%d\n", i, *data);
if (pthread_create(&threads[i], NULL, thread_function, (void *) data)) {
printf("ERROR creating thread %d\n", i + 1);
exit(1);
}
if (i == 0) {
thread_first_id = threads[i];
}
}
// Waiting threads to finish
for (i = 0; i < threads_count; i++) {
if (pthread_join(threads[i], NULL)) {
printf("\n ERROR joining thread"); exit(1);
}
}
pthread_exit(NULL);
}
Build:
gcc thread.c -lpthread -lrt -lm
Run: a.out <ITERATIONS> <THREADS COUNT>
time ./a.out 10000000 7
Posts
