多线程的互斥锁的运用

/* thread_mutex.c */
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

#define THREAD_NUMBER    3    /* 线程数 */
#define REPEAT_NUMBER    3    /* 每个线程的任务数 */
#define DELAY_TIME_LEVELS    10.0    /* 任务之间的最大时间间隔 */
pthread_mutex_t mutex;

void* thrd_func(void* arg)
{
int thrd_num = (int)arg;
int delay_time = 0, count = 0;
int res;

/* 互斥锁上锁 */
res = pthread_mutex_lock(&mutex);
if(res)
{
printf("Thread %d lock failed\n", thrd_num);
pthread_exit(NULL);
}
printf("Thread %d is starting\n", thrd_num);
for(count = 0; count < REPEAT_NUMBER; count++)
{
delay_time = (int)(rand() * DELAY_TIME_LEVELS/(RAND_MAX)) + 1;
sleep(delay_time);
printf("\tThread %d: job %d delay = %d\n", thrd_num, count, delay_time);
}
printf("Thread %d finished \n", thrd_num);
pthread_exit(NULL);
}

int main(void)
{
pthread_t thread[THREAD_NUMBER];
int no = 0, res;
void* thrd_ret;

srand(time(NULL));
/* 互斥锁初始化 */
pthread_mutex_init(&mutex, NULL);
for(no = 0; no < THREAD_NUMBER; no++)
{
res = pthread_create(&thread[no], NULL, thrd_func, (void*)no);
if(res != 0)
{
printf("Create thread %d failed\n", no);
exit(res);
}
}
printf("Create threads success\n Waiting for threads to finish...\n");
for(no = 0; no < THREAD_NUMBER; no++)
{
res = pthread_join(thread[no],&thrd_ret);
if(!res)
{
printf("Thread %d joined\n", no);
}
else
{
printf("Thread %d joined failed\n", no);
}
/* 互斥锁解锁 */
pthread_mutex_unlock(&mutex);
}
pthread_mutex_destroy(&mutex);
return 0;
}