Linux线程终止

      进程中的任一线程调用了exit，_Exit或者_exit，那么整个进程都会终止。

      单个线程在不终止整个进程的情况下停止它的控制流，有三种方式：

（1）线程只是从启动例程中返回，返回值是线程的退出码。

（2）线程可以被同一进程中的其他线程取消。

（3）线程调用pthread_exit。

1、单个线程调用exit，_Exit或者_exit

void* task1(void* arg)
{
    while (1) {sleep(1);printf("thread1 running...\n");}
    return NULL;
}

void* task2(void *arg)
{
　　while (1) {sleep(1);printf("thread2 running...\n");}

　　return NULL;
}

void* task3(void *arg)
{
    int i = 0;
    while (i++ < 5) {sleep(1);printf("thread3 running...\n");}
    exit(1);
    //_Exit(1);
    //_exit(1);
    return NULL;
}

int main(int argc, char *argv[])
{
    pthread_t thrd1, thrd2, thrd3;

    pthread_create(&thrd1, NULL, (void*)task1, NULL);
    pthread_create(&thrd2, NULL, (void*)task2, NULL);
    pthread_create(&thrd3, NULL, (void*)task3, NULL);

    pthread_join(thrd1, NULL);
    pthread_join(thrd2, NULL);
    pthread_join(thrd3, NULL);

    printf("Main thread exit...\n");
    return 0;
}

程序输出：

[root@robot ~]# vim thread_exit.c
[root@robot ~]# gcc thread_exit.c -lpthread -o thread_exit
[root@robot ~]# ./thread_exit
thread2 running...
thread3 running...
thread1 running...
thread2 running...
thread3 running...
thread1 running...
thread2 running...
thread3 running...
thread1 running...
thread2 running...
thread3 running...
thread1 running...
thread2 running...
thread3 running...
[root@robot ~]#

这里可以看到调用exit、_Exit、_exit会使整个进程退出。
2、单个线程调用pthread_exit

void pthread_exit(void* rval_ptr);

rval_ptr是一个无类型指针，可以通过调用pthread_join函数访问到这个指针。

void* task1(void* arg)
{
    int i = 0;
    while (i++ < 5) { sleep(1); printf("thread1 running...\n"); }
    pthread_exit((void*)23);

    return NULL;
}

int main(int argc, char *argv[])
{
    pthread_t thrd1, thrd2, thrd3;
    void* tret;

    pthread_create(&thrd1, NULL, (void*)task1, NULL);
    pthread_join(thrd1, &tret);

    printf("thread1 return code:%d\n", (int)tret);
    printf("Main thread exit...\n");
    return 0;
}

程序输出：

[root@robot ~]# gcc thread_exit.c -lpthread -o thread_exit
[root@robot ~]# ./thread_exit
thread1 running...
thread1 running...
thread1 running...
thread1 running...
thread1 running...
thread1 return code:23
Main thread exit...
[root@robot ~]#