条件变量pthread_cond_t

#include 
#include 
#include 
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;/*初始化互斥锁*/
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;/*初始化条件变量*/
void *thread1(void *);
void *thread2(void *);
int i=1;
int main(void)
{
    pthread_t t_a;
    pthread_t t_b;
    pthread_create(&t_a,NULL,thread1,(void *)NULL);/*创建进程t_a*/
    pthread_create(&t_b,NULL,thread2,(void *)NULL); /*创建进程t_b*/
    pthread_join(t_a, NULL);/*等待进程t_a结束*/
    pthread_join(t_b, NULL);/*等待进程t_b结束*/
    pthread_mutex_destroy(&mutex);
    pthread_cond_destroy(&cond);
    exit(0);
}
void *thread1(void *junk)
{
    for(i=1;i<=6;i++)
    {
        pthread_mutex_lock(&mutex);/*锁住互斥量*/
        printf("thread1: lock %d\n", __LINE__);
        if(i%3==0){
            printf("thread1:signal 1  %d \n", __LINE__);
            pthread_cond_signal(&cond);/*条件改变，发送信号，通知t_b进程*/
            printf("thread1:signal 2  %d\n", __LINE__);
            sleep(1);
        }
        pthread_mutex_unlock(&mutex);/*解锁互斥量*/
        printf("thread1: unlock %d\n\n", __LINE__);
        sleep(1);
    }
}
void *thread2(void *junk)
{
    while(i<6)
    {
        pthread_mutex_lock(&mutex);
        printf("thread2: lock %d\n", __LINE__);
        if(i%3!=0){
            printf("thread2: wait 1  %d\n", __LINE__);
            pthread_cond_wait(&cond,&mutex);/*解锁mutex，并等待cond改变*/
            printf("thread2: wait 2  %d\n", __LINE__);
        }
        pthread_mutex_unlock(&mutex);
        printf("thread2: unlock %d\n\n", __LINE__);
        sleep(1);
    }
}

[root@panda huang]# gcc 1.c -lpthread -o tcd

[root@panda huang]# ./tcd

thread2: lock 43
thread2: wait 1  45
thread1: lock 26
thread1: unlock 34


thread1: lock 26
thread1: unlock 34


thread1: lock 26
thread1:signal 1  28 
thread1:signal 2  30
thread1: unlock 34


thread2: wait 2  47
thread2: unlock 50


thread2: lock 43
thread2: unlock 50


thread1: lock 26
thread1: unlock 34


thread2: lock 43
thread2: wait 1  45
thread1: lock 26
thread1: unlock 34


thread1: lock 26
thread1:signal 1  28 
thread1:signal 2  30
thread1: unlock 34


thread2: wait 2  47
thread2: unlock 50