多线程编程之：Linux线程编程
（3）使用实例。
下面的实例是在9.2.1小节示例代码的基础上增加互斥锁功能，实现原本独立与无序的多个线程能够按顺序执行。
/*thread_mutex.c*/
#include stdio.h>
#include stdlib.h>
#include pthread.h>
#define THREAD_NUMBER 3 /* 线程数 */
#define REPEAT_NUMBER 3 /* 每个线程的小任务数 */
#define DELAY_TIME_LEVELS 10.0 /*小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 failedn, thrd_num);
pthread_exit(NULL);
}
printf(Thread %d is startingn, 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 = %dn,
thrd_num, count, delay_time);
}
printf(Thread %d finishedn, 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 failedn, no);
exit(res);
}
}
printf(Create treads successn 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 joinedn, no);
}
else
{
printf(Thread %d join failedn, no);
}
/* 互斥锁解锁 */
pthread_mutex_unlock(mutex);
}
pthread_mutex_destroy(mutex);
return 0;
}
该实例的运行结果如下所示。这里3个线程之间的运行顺序跟创建线程的顺序相同。
$ ./thread_mutex
Create treads success
Waiting for threads to finish...
Thread 0 is starting
Thread 0: job 0 delay = 7
Thread 0: job 1 delay = 7
Thread 0: job 2 delay = 6
Thread 0 finished
Thread 0 joined
Thread 1 is starting
Thread 1: job 0 delay = 3
Thread 1: job 1 delay = 5
Thread 1: job 2 delay = 10
Thread 1 finished
Thread 1 joined
Thread 2 is starting
Thread 2: job 0 delay = 6
Thread 2: job 1 delay = 10
Thread 2: job 2 delay = 8
Thread 2 finished
Thread 2 joined
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