关于Linux 线程pthread_join的用法

发布网友发布时间：2022-04-19 22:23

共2个回答

热心网友时间：2023-01-21 22:55

Linux系统pthread_join用于挂起当前线程（调用pthread_join的线程），直到thread指定的线程终止运行为止，当前线程才继续执行。

案例代码：

/*******************************************
**    Name:pthread_join.c
**    用于Linux下多线程学习
**    案例解释线程的暂停和结束
**    Author:admin
**    Date:2015/8/11
**    Copyright (c) 2015,All Rights Reserved!
**********************************************
#include <pthread.h>
#include <unistd.h>
#include <stdio.h>
void *thread(void *str)
{
    int i;
    //不调用pthread_join线程函数
    for (i = 0; i < 10; ++i)
    {
        sleep(2);
        printf( "This in the thread : %d\n" , i );
    }
    return NULL;
}

int main()
{
    pthread_t pth;
    int i;
    int ret = pthread_create(&pth, NULL, thread, (void *)(i));
    //调用pthread_join线程函数
    pthread_join(pth, NULL);
    for (i = 0; i < 10; ++i)
    {
        sleep(1);
        printf( "This in the main : %d\n" , i );
    }

    return 0;
}

通过Linux下shell命令执行上面的案例代码：

[root@localhost src]# gcc pthread_join.c -lpthread
[root@localhost src]# ./a.out
This in the main : 0
This in the thread : 0
This in the main : 1
This in the main : 2
This in the thread : 1
This in the main : 3
This in the main : 4
This in the thread : 2
This in the main : 5
This in the main : 6
This in the thread : 3
This in the main : 7
This in the main : 8
This in the thread : 4
This in the main : 9

子线程还没有执行完毕，main函数已经退出，那么子线程也就退出了，“pthread_join(pth, NULL);”函数起作用。

[root@localhost src]# gcc pthread_join.c -lpthread
[root@localhost src]# ./a.out
This in the thread : 0
This in the thread : 1
This in the thread : 2
This in the thread : 3
This in the thread : 4
This in the thread : 5
This in the thread : 6
This in the thread : 7
This in the thread : 8
This in the thread : 9
This in the main : 0
This in the main : 1
This in the main : 2
This in the main : 3
This in the main : 4
This in the main : 5
This in the main : 6
This in the main : 7
This in the main : 8
This in the main : 9

这说明pthread_join函数的调用者在等待子线程退出后才继续执行。

热心网友时间：2023-01-22 00:13

这是随机情况，由系统调度决定，不是唯一的结果，你可以尝试这样改：ret=pthread_create(&threadids[i], NULL, myThread, (void*)i);
sleep(1);
这样就是按顺序创建线程