关于linux中的清除问题
本帖最后由 chuwangmvp 于 2012-4-11 16:14 编辑#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
void *clean(void *arg)
{
printf("cleanup :%s\n",(char *)arg);
return (void *)0;
}
void *thr_fn1(void *arg)
{
printf("thread 1 start\n");
pthread_cleanup_push( (void*)clean,"thread 1 first handler");
pthread_cleanup_push( (void*)clean,"thread 1 second hadler");
printf("thread 1 push complete\n");
if(arg)
{
return((void *)4);
}
pthread_cleanup_pop(0);
pthread_cleanup_pop(0);
return (void *)4;
}
void *thr_fn2(void *arg)
{
printf("thread 2 start\n");
pthread_cleanup_push( (void*)clean,"thread 2 first handler");
pthread_cleanup_push( (void*)clean,"thread 2 second handler");
printf("thread 2 push complete\n");
if(arg)
{
pthread_exit((void *)2);
}
pthread_cleanup_pop(0);
pthread_cleanup_pop(0);
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)
{
printf("error .... \n");
return -1;
}
err=pthread_create(&tid2,NULL,thr_fn2,(void *)1);
if(err!=0)
{
printf("error .... \n");
return -1;
}
err=pthread_join(tid1,&tret);
if(err!=0)
{
printf("error .... \n");
return -1;
}
printf("thread 1 exit code %d\n",(int)tret);
err=pthread_join(tid2,&tret);
if(err!=0)
{
printf("error .... ");
return -1;
}
printf("thread 2 exit code %d\n",(int)tret);
return 1;
}
运行结果:
thread 2 start
thread 2 push complete
clean up: thread 2 second handler
clean up: thread 2 first handler
thread 1 start
thread 1 push complete
thread 1 exit code 4
thread 2 exit code 2
我当时猜想的是:
thread 1 start
thread 1 push complete
thread 2 start
thread 2 push complete
clean up: thread 2 second handler
clean up: thread 2 first handler
thread 1 exit code 4
thread 2 exit code 2
问题:
为什么是thread 2 先执行了的。。。。 1. 线程的执行顺序是靠调度器决定的
2. pthread_cleanup_pop完全用错了,好好看man theophilus 发表于 2012-4-11 16:37 static/image/common/back.gif
1. 线程的执行顺序是靠调度器决定的
2. pthread_cleanup_pop完全用错了,好好看man ...
1.能不能提供下资料,具体的看下咯;
2,pthread_cleanup_pop我是看国嵌的用法用的,里面的参数决定是否执行接下来的程序(非0:执行; 0:不执行); 1. 我是记得APUE的Thread那章就有讲(有点久了,记不太清)。要保证执行顺序,需要同步机制。等会我找找
2. 我说错了,那段代码是对的,我太二逼了。
打字的时候翻了翻APUE2,有这么一句
When a thread is created, there is no guarantee which runs first: the newly created thread or the calling thread.
再往后翻一点,那段代码就是APUE的嘛,我二到极点了,看来看书不认真啊。
页:
[1]