相关疑难解决方法(0)

在下面的代码示例中,程序执行永远不会结束.

它创建一个线程,在终止之前等待全局bool设置true.只有一位作家和一位读者.我相信允许循环继续运行的唯一情况是bool变量是否为false.

这怎么可能是bool变量,最终处于不一致的状态只是一个作家？

#include <iostream>
#include <pthread.h>
#include <unistd.h>

bool done = false;

void * threadfunc1(void *) {
    std::cout << "t1:start" << std::endl;
    while(!done);
    std::cout << "t1:done" << std::endl;

    return NULL;
}

int main()
{
    pthread_t threads;

    pthread_create(&threads, NULL, threadfunc1, NULL);

    sleep(1);

    done = true;
    std::cout << "done set to true" << std::endl;

    pthread_exit(NULL);

    return 0;
}

在C程序中,PTHREAD_CANCEL_ASYNCHRONOUS只要从父线程触发pthread_cancel ,我就会立即取消该线程.但它导致整个过程因Segmentation Fault而崩溃.子线程的工作是从数据库服务器获取一些数据.我的逻辑是,如果它在10秒内没有获取数据,那么该线程应该从父线程中被杀死.

我只想杀死子线程,而不是整个过程.

struct str_thrd_data
{
        SQLHANDLE hstmt;
        int rc;
        bool thrd_completed_flag;
};


void * str_in_thread_call(void *in_str_arg)
{
        int thrd_rc;
        struct str_thrd_data *str_arg;
        str_arg = in_str_arg;

        thrd_rc = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
        if (thrd_rc != 0)
               handle_error_en(thrd_rc, "pthread_setcancelstate");

        thrd_rc = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
        if (thrd_rc != 0)
               handle_error_en(thrd_rc, "pthread_setcancelstate");

        thrd_rc = pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
        if (thrd_rc != 0)
               handle_error_en(thrd_rc, "pthread_setcanceltype");
        // Code to call SQL Dynamic Query from a Database Server. This takes time more than 10 seconds.
      thrd_rc …