cout - Simple Detached pthread 不会取消! (即使互斥， cout 也会阻塞和交错)

Question

我在这里有一个难题，我无法解决，也没有在网上找到正确的答案:

我创建了一个带有清理路由的分离线程，问题是在我的 Imac 和 Ubuntu 9.1(双核)上。我无法正确取消空闲代码中的分离线程:

#include <iostream>
#include <pthread.h>
#include <sched.h>
#include <signal.h>

#include <time.h>

pthread_mutex_t mutex_t;

using namespace std;

static void cleanup(void *arg){
    pthread_mutex_lock(&mutex_t);
    cout << " doing clean up"<<endl;
    pthread_mutex_unlock(&mutex_t);
}


static void *thread(void *aArgument)
{

    pthread_setcancelstate(PTHREAD_CANCEL_ENABLE,NULL);
    pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED,NULL);

    pthread_cleanup_push(&cleanup,NULL);
    int n=0;
    while(1){
        pthread_testcancel();
        sched_yield();
        n++;

        pthread_mutex_lock(&mutex_t);
        cout << " Thread 2: "<< n<<endl; // IF I remove this endl;  --> IT WORKS!!??
        pthread_mutex_unlock(&mutex_t);

    }
    pthread_cleanup_pop(0);

    return NULL;
}


int main()
{

    pthread_t thread_id;

    pthread_attr_t attr;
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED);

    int error;

    if (pthread_mutex_init(&mutex_t,NULL) != 0) return 1;

    if (pthread_create(&thread_id, &attr, &(thread) , NULL) != 0) return 1;

    pthread_mutex_lock(&mutex_t);
    cout << "waiting 1s for thread...\n" <<endl;
    pthread_mutex_unlock(&mutex_t);

    int n =0;

    while(n<1E3){
        pthread_testcancel();
        sched_yield();
        n++;

        pthread_mutex_lock(&mutex_t);
        cout << " Thread 1: "<< n<<endl;
        pthread_mutex_unlock(&mutex_t);
    }

    pthread_mutex_lock(&mutex_t);
    cout << "canceling thread...\n" <<endl;
    pthread_mutex_unlock(&mutex_t);

    if (pthread_cancel(thread_id) == 0)
    {
        //This doesn't wait for the thread to exit
        pthread_mutex_lock(&mutex_t);
        cout << "detaching thread...\n"<<endl;
        pthread_mutex_unlock(&mutex_t);

        pthread_detach(thread_id);

        while (pthread_kill(thread_id,0)==0)
        {
                sched_yield();
        }

        pthread_mutex_lock(&mutex_t);
        cout << "thread is canceled";
        pthread_mutex_unlock(&mutex_t);

    }

    pthread_mutex_lock(&mutex_t);
    cout << "exit"<<endl;
    pthread_mutex_unlock(&mutex_t);

    return 0;
}

当我用 printf() 替换 Cout 时，我一直工作到最后“退出”，但是使用 cout(甚至锁定)，可执行文件在输出“分离线程...

从专业人士那里知道会很酷，这里的问题是什么？。
为什么即使 cout 被互斥锁锁定，这也不起作用!？

Answer 1

问题在于 COUT 有一个隐式取消点!

我们需要这样编码:

pthread_setcancelstate(PTHREAD_CANCEL_ENABLE,NULL);
    pthread_testcancel();
    pthread_setcancelstate(PTHREAD_CANCEL_DISABLE,NULL);

并在开头制作线程:

pthread_setcancelstate(PTHREAD_CANCEL_DISABLE,NULL);

这确保只有 pthread_cancel() 有取消点......