スレッドの同期２

/* * sample program * synchronous of threads test program */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <errno.h> #include <pthread.h> #define MAX_THREADS 10 #define MAX_CNT 10000 int grobal_cnt; pthread_mutex_t mutex, mutex_start; pthread_cond_t cond_start; pthread_t thread_id[MAX_THREADS]; void *thread(void*); int main(void) { int i = 0; printf("sample program(%s) start\n", __FILE__); pthread_mutex_init(&mutex, NULL); pthread_mutex_init(&mutex_start, NULL); pthread_cond_init(&cond_start, NULL); /* create new threads */ for(i = 0; i < MAX_THREADS; i++){ if(pthread_create(&thread_id[i], NULL, thread, (void *)&thread_id[i]) < 0){ perror("pthread_create error"); exit(1); } } sleep(3); pthread_cond_broadcast(&cond_start); /* wait for the end of threads */ for(i = 0; i < MAX_THREADS; i++){ if(pthread_join(thread_id[i], NULL) < 0){ perror("pthread_join error"); exit(1); } } printf("grobal_cnt = %d\n", grobal_cnt); return 0; } void *thread(void *arg) { int i = 0, cnt = 0; pthread_t *pthread_id; pthread_id = (pthread_t *)arg; printf("thread[%lu] start\n", *pthread_id); pthread_mutex_lock(&mutex_start); pthread_cond_wait(&cond_start, &mutex_start); pthread_mutex_unlock(&mutex_start); /* counter increment */ for(i = 0; i < MAX_CNT; i++){ pthread_mutex_lock(&mutex); cnt = grobal_cnt; cnt++; grobal_cnt = cnt; pthread_mutex_unlock(&mutex); } printf("thread[%lu] end\n", pthread_self()); pthread_exit(0); }