哪里导致僵局？

Question

我打算让两个线程等待来自第三个线程的信号.

这两个线程执行相同的工作,但其中只有一个一次获取信号.一旦满足某个条件(捕获的信号数量),它们就会自行终止.

然后最后主线程取消第三个线程.

我遇到了僵局,但无法弄清问题在哪里.

#include <pthread.h>
#include <stdio.h>

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

int n = 0;
int count = 0;

void* func1(void *ptr)
{
    while(1)
    {
        pthread_mutex_lock(&mutex);

        // wait for func3 to signal
        pthread_cond_wait(&cond, &mutex);
        count++;

        if(count > 10)
        {
            printf("number %d terminate func1\n", n);
            return (NULL);
        }
        else
        {
            printf("func1 got number:%d\n", n);
        }
        pthread_mutex_unlock(&mutex);
    }
}

void* func2(void *ptr)
{
    while(1)
    {
        pthread_mutex_lock(&mutex);

        // wait for func3 to signal
        pthread_cond_wait(&cond, &mutex);
        count++;

        if(count > 10)
        {
            printf("number %d terminate func2\n", n);
            return (NULL);
        }
        else
        {
            printf("func2 got number:%d\n", n);
        }
        pthread_mutex_unlock(&mutex);
    }
}    

void* func3(void *ptr)
{
    while(1)
    {
        pthread_mutex_lock(&mutex);
        n++;
        pthread_cond_signal(&cond);
        pthread_mutex_unlock(&mutex);
    }
}


int main(int argc, char *argv[])
{
    pthread_t t1, t2, t3;

    pthread_create(&t1, NULL, func1, NULL);
    pthread_create(&t2, NULL, func2, NULL);
    pthread_create(&t3, NULL, func3, NULL);

    pthread_join(t1, NULL);
    pthread_join(t2, NULL);

    pthread_cancel(t3);

    return 0;
}

Answer 1

你不是解锁互斥时func1或func2退出.