|
|
|
|
  请问下面的这两段多线程程序的差别 - zhengdalx [ 2005-03-30 22:54 | 3,409 byte(s)]
Re: 请问下面的这两段多线程程序的差别 - vxworkslinux [ 2005-03-31 13:27 | 323 byte(s)]
Re: 请问下面的这两段多线程程序的差别 - zhengdalx [ 2005-03-31 23:54 | 331 byte(s)]
Re: 请问下面的这两段多线程程序的差别 - vxworkslinux [ 2005-04-01 22:30 | 5,930 byte(s)]
Re: 请问下面的这两段多线程程序的差别 - zhengdalx [ 2005-04-03 23:38 | 138 byte(s)]
Re: 请问下面的这两段多线程程序的差别 - zhengdalx [ 2005-04-02 00:14 | 134 byte(s)]
Re: 请问下面的这两段多线程程序的差别 - zhengdalx [ 2005-03-31 23:51 | 2,290 byte(s)]
Re: 请问下面的这两段多线程程序的差别 - zhengdalx [ 2005-03-31 23:40 | 100 byte(s)]
Re: 请问下面的这两段多线程程序的差别 - vxworkslinux [ 2005-04-01 19:26 | 3,011 byte(s)]
Re: 请问下面的这两段多线程程序的差别 - zhengdalx [ 2005-04-02 00:03 | 142 byte(s)]
|
|
|
|
[Original]
[Print]
[Top]
|
#include <iostream>
using namespace std;
#include <pthread.h>
pthread_cond_t cond=PTHREAD_COND_INITIALIZER;
pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;
bool flag=true;
void *thread_run(void *)
{
int state;
pthread_mutex_lock(&mutex);
pthread_cond_signal(&cond);
cout<<"------------send a signal"<<endl;
pthread_mutex_unlock(&mutex);
cout<<"------------thread start"<<endl;
while(true){
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE , &state);
cout<<"-----------thread loop"<<endl;
for(int i=0 ; i < 10000 ; i++);
cout<<"----------start to sleep"<<endl;
pthread_setcancelstate(state , &state);//enable to cancel the thread
sleep(1);
}
}
int main()
{
for(int i=0 ; i < 1000 ; i++){
pthread_t id;
cout<<"create a thread:"<<i<<endl;
pthread_mutex_lock(&mutex);
pthread_create(&id , NULL , thread_run , NULL);
cout<<"start to wait"<<endl;
pthread_cond_wait(&cond , &mutex);
pthread_mutex_unlock(&mutex);
//cout<<"wait for the new thread to run"<<end;
//pthread_cond_wait(&cond , &mutex);
cout<<"cancel a thread"<<endl;
pthread_cancel(id);
void *reval;
cout<<"wait for a thread to die"<<endl;
pthread_join(id , &reval);
cout<<endl<<endl;
}
}
如果把thread_run改成如下：
void *thread_run(void *)
{
int state;
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE , &state);
pthread_mutex_lock(&mutex);
pthread_cond_signal(&cond);
cout<<"------------send a signal"<<endl;
pthread_mutex_unlock(&mutex);
cout<<"------------thread start"<<endl;
while(true){
cout<<"-----------thread loop"<<endl;
for(int i=0 ; i < 10000 ; i++);
cout<<"----------start to sleep"<<endl;
pthread_setcancelstate(state , &state);//enable to cancel the thread
sleep(1);
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE , &state);//disable to cancel the
thread
}
}
我发现好像只有在调用像sleep()这样的函数(会让线程挂起的函数)的时候被cancel掉，才能整个�
绦虿拍苷Ｔ诵小Ｎ也幻靼孜裁椿嵴庋�
请大牛指教
|
|
|
[Original]
[Print]
[Top]
|
|
[Original]
[Print]
[Top]
|
上个帖子你问的也是多线程编程，请原谅我上个帖子回得很草率
后来我把你上个帖子的程序测试了一下，发现没问题，我以为你已经弄清楚了，所以就没有再跟帖。
这次你又发帖子问关于多线程的问题，我还是没看懂你要问什么。好像是关于退出点的问题（我猜的），
你可以man一下，里面有关于退出点的概念，也许会对你有所帮助
|
|
[Original]
[Print]
[Top]
|
|
[Original]
[Print]
[Top]
|
我的意思就是在第一个thread_run()函数中
void *thread_run(void *)
{
int state;
pthread_mutex_lock(&mutex);
pthread_cond_signal(&cond);
cout<<"------------send a signal"<<endl;
pthread_mutex_unlock(&mutex);
cout<<"------------thread start"<<endl;
while(true){
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE , &state);
cout<<"-----------thread loop"<<endl;
for(int i=0 ; i < 10000 ; i++);
cout<<"----------start to sleep"<<endl;
pthread_setcancelstate(state , &state);//enable to cancel the thread
sleep(1);
}
}
程序在运行到函数的前半部分的时候可以被pthread_cancel()终止掉的，所以程序运行的时候新创建的线程经常不能被顺利的终止掉
而如果我把程序改成下面的样子
void *thread_run(void *)
{
int state;
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE , &state);
pthread_mutex_lock(&mutex);
pthread_cond_signal(&cond);
cout<<"------------send a signal"<<endl;
pthread_mutex_unlock(&mutex);
cout<<"------------thread start"<<endl;
while(true){
cout<<"-----------thread loop"<<endl;
for(int i=0 ; i < 10000 ; i++);
cout<<"----------start to sleep"<<endl;
pthread_setcancelstate(state , &state);//enable to cancel the thread
sleep(1);
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE , &state);//disable to cancel thethread
}
}
的时候，由于新的线程只有在运行到sleep的时候才有可能被pthread_cancel终止掉。奇怪的是，如果是用下面的这个thread_run就不会有问题了。
我是不明白为什么会这个样子
|
|
|
[Original]
[Print]
[Top]
|
|
[Original]
[Print]
[Top]
|
我感觉新创建的线程不能被顺利终止的时候好像线程调度的情况如下，假如
有两个线程A,B，
线程A执行pthread_cancel()，想终止线程B
调度到线程B执行
线程B被终止
线程A调用pthread_join()，线程A永远被阻塞
这个是我的个人想法，不知道对不对
不知道现在你有没有弄清楚我的意思？
|
|
|
[Original]
[Print]
[Top]
|
|
[Original]
[Print]
[Top]
|
上个贴子你的源码如下:
#include <iostream>
using namespace std;
#include <pthread.h>
pthread_cond_t cond=PTHREAD_COND_INITIALIZER;
pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;
void *thread_run(void *)
{
cout<<"------------thread start"<<endl;
//pthread_cond_signal(&cond);
int state;
while(true){
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE , &state);
cout<<"-----------thread loop"<<endl;
for(int i=0 ; i < 10000 ; i++);
cout<<"----------start to sleep"<<endl;
pthread_setcancelstate(state , &state);
sleep(1);
}
}
int main()
{
for(int i=0 ; i < 1000 ; i++){
pthread_t id;
cout<<"create a thread"<<endl;
pthread_create(&id , NULL , thread_run , NULL);
cout<<"cancel a thread"<<endl;
pthread_cancel(id);
void *reval;
cout<<"wait for a thread to die"<<endl;
pthread_join(id , &reval);
cout<<endl<<endl;
}
}
我执行的结果如下:(gcc version 3.3.3 20040412 (Red Hat Linux 3.3.3-7))
create a thread
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
wait for a thread to die
create a thread
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
wait for a thread to die
create a thread
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
wait for a thread to die
create a thread
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
wait for a thread to die
create a thread
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
wait for a thread to die
create a thread
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
wait for a thread to die
create a thread
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
wait for a thread to die
.......
|
|
|
[Original]
[Print]
[Top]
|
|
[Original]
[Print]
[Top]
|
我测试这个贴子的第一种方案(改了点东西,你看看),
#include <iostream>
using namespace std;
#include <pthread.h>
pthread_cond_t cond=PTHREAD_COND_INITIALIZER;
pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER;
bool flag=true;
#if 1
void *thread_run(void *)
{
int state;
pthread_mutex_lock(&mutex);
pthread_cond_signal(&cond);
cout<<"------------send a signal"<<endl;
pthread_mutex_unlock(&mutex);
//printf("test!
");-----------------------------------------------------(1)
cout<<"------------thread start"<<endl;
while(true){
// pthread_testcancel();---------------------------------------------(0)
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE , &state);
cout<<"-----------thread loop"<<endl;
for(int i=0 ; i < 10000 ; i++);
cout<<"----------start to sleep"<<endl;
pthread_setcancelstate(state , &state);//enable to cancel the thread
sleep(1);
}
}
#endif
int main()
{
for(int i=0 ; i < 1000 ; i++){
pthread_t id;
cout<<"create a thread:"<<i<<endl;
pthread_mutex_lock(&mutex);
pthread_create(&id , NULL , thread_run , NULL);
cout<<"start to wait"<<endl;
pthread_cond_wait(&cond , &mutex);
pthread_mutex_unlock(&mutex);
//cout<<"wait for the new thread to run"<<end;
//pthread_cond_wait(&cond , &mutex);
//usleep(1);-------------------------------------------------------(2)
cout<<"cancel a thread"<<endl;
if( pthread_cancel(id) == 0 )
{
perror("pthread_cancel:error");
}
void *reval;
cout<<"wait for a thread to die"<<endl;
if( pthread_join(id , &reval) == 0 )
{
perror("pthread_join:error");
}
cout<<endl<<endl;
}
}
输出如下:
create a thread:0
start to wait
------------send a signal
cancel a thread
pthread_cancel:error: Success
wait for a thread to die
FATAL: exception not rethrown
------------thread start
已放弃
这个说明pthread_cancel成功,还没有执行到pthread_join
首先我怀疑是退出点的问题,所以在(0)处加了pthread_testcancel,但是输出依然错误(如上)
后来我加上(1),执行就没问题,但是输出不是Success
结果如下:
create a thread:0
start to wait
------------send a signal
cancel a thread
pthread_cancel:error: Success
wait for a thread to die
pthread_join:error: Illegal seek
test!
create a thread:1
start to wait
------------send a signal
cancel a thread
pthread_cancel:error: Illegal seek
wait for a thread to die
pthread_join:error: Illegal seek
test!
create a thread:2
start to wait
------------send a signal
cancel a thread
pthread_cancel:error: Illegal seek
wait for a thread to die
pthread_join:error: Illegal seek
test!
create a thread:3
start to wait
------------send a signal
cancel a thread
pthread_cancel:error: Illegal seek
wait for a thread to die
pthread_join:error: Illegal seek
test!
.......
最后去掉(1),加上(2):执行就也没问题,但是输出也并不是Success,与(1)不同的是:(2)在sleep处退出,(1)在printf处退出
结果如下:
create a thread:0
start to wait
------------send a signal
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
pthread_cancel:error: Success
wait for a thread to die
pthread_join:error: Illegal seek
create a thread:1
start to wait
------------send a signal
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
pthread_cancel:error: Illegal seek
wait for a thread to die
pthread_join:error: Illegal seek
create a thread:2
start to wait
------------send a signal
------------thread start
-----------thread loop
----------start to sleep
cancel a thread
pthread_cancel:error: Illegal seek
wait for a thread to die
pthread_join:error: Illegal seek
......
原因我也不太清楚,请牛人指点
|
|
|
[Original]
[Print]
[Top]
|
|
|
声明: 本页内容为中国Linux论坛的内容镜像，文章的版权以及其他所有的相关权利属于中国Linux论坛和相应文章的作者，如果转载，请注明文章来源及相关版权信息。