pthread_cancel()不会像应该的那样取消线程

我正在为我的OS类项目测试一个信号处理程序。

不幸的是,我的代码不起作用。

这是我的虚拟线程任务,我想用SIGINT停止它

 static void * dummyTask(){
   pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
   pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL);
   while(1){
      pthread_testcancel();
      printf(" Hello!\n");
      sleep(2);
   }
   return NULL;
}

 int main(){
   //need to the signal handler thread, so it can kill all the threads with cancel
   pthread_t **thids = malloc( 2 * sizeof(pthread_t *));
   sigset_t set;
   pthread_t signalHandlerThread;

   sigemptyset(&set);
   sigaddset(&set, SIGINT);
   //s is for error checking, not importanto now
   int s = pthread_sigmask(SIG_BLOCK, &set, NULL);

   //shParam: signalHandlerParam
   signalHParam *shParam = malloc(sizeof(signalHParam));
    shParam->set = &set;
    shParam->arrayOfThIDs = thids;
   s = pthread_create(&signalHandlerThread, NULL, signalHandlerTask, (void *) shParam);

   for(int i = 0; i < 2; i ++){
     pthread_t dummyThread;
     pthread_create(&dummyThread, NULL, &dummyTask, NULL);
     thids[i] = &dummyThread;
   }

   pause();
   //pthread_join(signalHandlerThread, NULL);
   return 1;
}

正如您所看到的,signalHandlerThread执行一个名为signalHandlerTask的函数,它是:

static void *signalHandlerTask(void *shParam){
   signalHParam *tmp = (signalHParam *) shParam;
   sigset_t *set = tmp->set;
   int s, sig;

    int i = sigismember(set, SIGINT);
    if(i != 1)
      printf("error\n");
   while(1 == 1){
      s = sigwait(set, &sig);

        if(sig == SIGINT){
            printf("\n----- signal recived ----\n");
         //function that use the array to kill threads
            killThreads(tmp->arrayOfThIDs);
            pthread_exit(NULL); //kill the signal handler thread
        }
    }
}

typedef struct{
   pthread_t **arrayOfThIDs;
   sigset_t *set;
} signalHParam;

最后,我们谈到了真正的问题。我创建了killThreads函数,如下所示:

void killThreads(pthread_t **thids){
    for(int i = 0; i < 2; i++){
        int r = pthread_cancel(*thids[i]);
        if(r != 0)
            printf("error!! %d\n", r);
            //r is 3, why??
            pthread_join(*thids[i], NULL);
    }
}

pthread_cancel(*thids[i]) 不工作,线程是活着的,我不明白为什么

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <assert.h>
#include <string.h>
#include <error.h>
#include <unistd.h>
#include <errno.h>

typedef struct{
   pthread_t **arrayOfThIDs;
   sigset_t *set;
} signalHParam;

void killThreads(pthread_t **thids){
    //termino il threadListener, e tutti i thread nel thread pool 
    for(int i = 0; i < 2; i++){

        //FAI ANCHE SU PROGETTO!!
        int r = pthread_cancel(*thids[i]);
        if(r != 0)
         printf("pthread_cancel failed: %s\n", strerror(r));
        //FAI ANCHE SU PROGETTO!!
        pthread_join(*thids[i], NULL);
    }

}

static void *signalHandlerTask(void *shParam){
    signalHParam *tmp = (signalHParam *) shParam;
   sigset_t *set = tmp->set;
   int s, sig;

    int i = sigismember(set, SIGINT);
    if(i != 1)
      printf("error\n");
   while(1 == 1){
      s = sigwait(set, &sig);

        if(sig == SIGINT){
            printf("\n----- signal recived ----\n");
         //function that use the array to kill threads
            killThreads(tmp->arrayOfThIDs);
            pthread_exit(NULL); //kill the signal handler thread
        }
    }
}
static void * dummyTask(){
   pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
   pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL);
   //printf("mo aspetto 10s\n");
   //sleep(10);
   while(1){
      pthread_testcancel();
      printf(" Ciao!\n");
      sleep(2);
   }
   return NULL;
}

int main(){
   //need to the signal handler thread, so it can kill all the threads with cancel
   pthread_t **thids = malloc( 2 * sizeof(pthread_t *));
   sigset_t set;
   pthread_t signalHandlerThread;

   sigemptyset(&set);
   sigaddset(&set, SIGINT);
   //s is for error checking, not importanto now
   int s = pthread_sigmask(SIG_BLOCK, &set, NULL);

   //shParam: signalHandlerParam
   signalHParam *shParam = malloc(sizeof(signalHParam));
    shParam->set = &set;
    shParam->arrayOfThIDs = thids;
   s = pthread_create(&signalHandlerThread, NULL, signalHandlerTask, (void *) shParam);

   for(int i = 0; i < 2; i ++){
     pthread_t dummyThread;
     pthread_create(&dummyThread, NULL, &dummyTask, NULL);
     thids[i] = &dummyThread;
   }

   pthread_join(signalHandlerThread, NULL);
   return 1;
}