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关于linux的线程清理函数pthread_cleanup_push的疑问

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悬赏园豆:20 [待解决问题]

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <string.h>

void cleanup(void *arg)
{
printf("cleanup: %s\n",(char *)arg);
}

void *thr_fn1(void *arg)
{
printf("thread 1 start\n");
pthread_cleanup_push(cleanup,"thread 1 first handler");
pthread_cleanup_push(cleanup,"thread 1 second handler");
printf("thread 1 push complete\n");
if(arg)
return ((void *)1);
pthread_cleanup_pop(1);
pthread_cleanup_pop(1);
return ((void *)1);
}

void *thr_fn2(void *arg)
{
printf("thread 2 start\n");
pthread_cleanup_push(cleanup,"thread 2 first handler");
pthread_cleanup_push(cleanup,"thread 2 second handler");
printf("thread 2 push complete\n");

if(arg)
{
pthread_exit((void *)2);
}
pthread_cleanup_pop(0); //取消第一个线程处理程序

pthread_cleanup_pop(0); //取消第二个线程处理程序

pthread_exit((void *) 2);
}


int main(void)

{
int err;
pthread_t tid1,tid2;
void *tret;

err = pthread_create(&tid1,NULL,thr_fn1,(void *)1);
if( err != 0)
{
fprintf(stderr,"create thread1 failed: %s",strerror(err));
exit(1);
}

err = pthread_create(&tid2,NULL,thr_fn2,(void *)2);
if(err != 0){
fprintf(stderr,"create thread 2 failed: %s",strerror(err));
exit(1);
}

err = pthread_join(tid1,&tret);
if(err != 0){
fprintf(stderr,"thread1 join failed: %s",strerror(err));
exit(1);
}
printf("thread 1 exit code %d\n",(int)tret);
err = pthread_join(tid2,&tret);
if(err != 0){
fprintf(stderr,"thread2 join failed: %s",strerror(err));
exit(1);
}
printf("thread 2 exit code %d\n",(int) tret);
exit(0);
}

 

//为什么需要出现两个线程清理函数:

pthread_cleanup_push(cleanup,"thread 2 first handler"); 
pthread_cleanup_push(cleanup,"thread 2 second handler");

WEN.HQ的主页 WEN.HQ | 初学一级 | 园豆:182
提问于:2013-08-25 02:27
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所有回答(1)
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出现两个是为了看一下它们被调用的顺序与注册的顺序的关系。就好像atexit()函数一样,调用的顺序和注册的顺序相反,线程处理函数也一样,也是相反的。注册的时候,是先first后second,如果输出结果是先second后first的话,就知道相反顺序的。

Champ_Keh | 园豆:202 (菜鸟二级) | 2013-10-14 17:40
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