取消一个线程

#include <pthread.h>#include <stdio.h>#include <stdlib.h>void *thread_function(void *arg);int main(){    int res;    pthread_t a_thread;    void *thread_result;    res = pthread_create(&a_thread, NULL, thread_function, NULL);    if (res != 0)    {        perror("Thread create failed!");        exit(EXIT_FAILURE);    }    sleep(4);    printf("Canceling thread...\n");    res = pthread_cancel(a_thread);    if (res != 0)    {        perror("Thread cancel failed!");        exit(EXIT_FAILURE);    }    printf ("Waiting for thread to finished...\n");        res = pthread_join(a_thread, &thread_result);    if (res != 0)    {        perror ("Thread join failed!");        exit(EXIT_FAILURE);    }    printf("Thread canceled!");    exit(EXIT_FAILURE);}void *thread_function(void *arg){    int i;    int res;    res = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);    if (res != 0)    {        perror("Thread setcancelstate failed!");        exit(EXIT_FAILURE);    }    res = pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL);    if (res != 0)    {        perror("Thread setcanceltype failed!");        exit(EXIT_FAILURE);    }    printf("thread_function is running...\n");    for (i = 0; i < 10; i++)    {        printf("Thread is still running (%d)...\n", i);        sleep(1);    }    pthread_exit(0);}