c - pthread(段错误)

Question

我是韩国人，我不擅长英语，但如果你给我一个评论
我会很高兴并会尝试理解它。

例如，我创建了 10 个线程，并尝试在创建后加入它们并返回值。
但是当我加入最后一个线程时，出现了段错误。

结果是这样的..

Before Thread 1 create
After Thread 1 create
Before Thread 0 create
After Thread 0 create
Before Thread 1 join
After Thread 1 join
Before Thread 0 join
Segmentation Fault(core dumped)

当我创建 4 个线程时，它就像

Before Thread 3 create
After Thread 3 create
Before Thread 2 create
After Thread 2 create
Before Thread 1 create
After Thread 1 create
Before Thread 0 create
After Thread 0 create
Before Thread 3 join
After Thread 3 join
Before Thread 2 join
After Thread 2 join
Before Thread 1 join
After Thread 1 join
Before Thread 0 join
Segmentation Fault(core dumped)

我似乎找不到原因。

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

pthread_mutex_t mutex_lock;

struct arg_struct {
        int a;
        int b;
};

void *t_function(void *data) {
        pthread_mutex_lock(&mutex_lock);

        struct arg_struct *arg = (struct arg_struct *)data;
        long int s;

        s = arg->a;

        pthread_mutex_unlock(&mutex_lock);

        return (void **)s;
}

int main()
{
        int i;

        pthread_t p_thread[2];
        int thr_id;
        int status;

        struct arg_struct arg[2];

        for(i = 1; i >= 0; i--) {
                arg[i].a = i;
                arg[i].b = i;
        }

        pthread_mutex_init(&mutex_lock, NULL);

        for(i = 1; i >= 0; i--) {
                printf("Before Thread %d create\n", i);
                thr_id = pthread_create(&p_thread[i],NULL, t_function, (void *)&arg[i]);
                printf("After Thread %d create\n", i);
                usleep(1000);
        }

        int temp[2];

        for(i = 1; i >= 0; i--) {
                printf("Before Thread %d join\n", i);
                pthread_join(p_thread[i], (void**)&status);
                printf("After Thread %d join\n", i);
                temp[i] = status;
        }i

        printf("%d%d", temp[1], temp[0]);

        pthread_mutex_destroy(&mutex_lock);

        return 0;
}

Answer 1

    pthread_t p_thread[2];
    struct arg_struct arg[2];
    int temp[2];

你在这里只为两个元素分配了空间，所以如果你启动超过 2 个线程，你将跑到数组的末尾，并可能崩溃或破坏堆栈。

另外:

            pthread_join(p_thread[i], (void**)&status);

status 是一个int，而不是一个void *；尝试这样做将尝试将 void * 存储在 int 中。在许多 64 位平台上，这也会溢出(因为 void * 将是 8 个字节，而 int 是 4 个字节)。将 status 设为 void *，并停止尝试像这样消除编译器错误。它们是有原因的错误。