Linux pthread（分段错误）
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pthread (segmentation fault)
提问by IKS
I'm Korean and I'm not good at English but if you give me a comment down there
I will be very pleased and will try to understand it.
我是韩国人，英语不好，但如果你在下面给我评论，
我会很高兴，并会尝试理解它。
I created, for example, 10 threads and tried to join them after creation and return the value.
But when I join the last thread, I get a segmentation fault.
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，出现分段错误。
The result comes out like this..
结果出来了。。
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)
when I create 4 threads it's like
当我创建 4 个线程时，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)
I can't seem to find why.
我似乎无法找到原因。
#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;
}
采纳答案by bdonlan
pthread_t p_thread[2];
struct arg_struct arg[2];
int temp[2];
You only allocated space for two elements here, so if you launch more than 2 threads you'll run off the end of the array and potentially crash or corrupt the stack.
您在这里只为两个元素分配了空间，因此如果您启动 2 个以上的线程，您将运行到数组的末尾并可能导致堆栈崩溃或损坏。
Additionally:
此外：
pthread_join(p_thread[i], (void**)&status);
statusis an int, not a void *; attempting this will try to store a void *in an int. On many 64-bit platforms, this will also overflow (since void *will be 8 bytes while intis 4). Make statusa void *, and stop trying to cast away compiler errors like this. They're errors for a reason.
status是一个int，不是一个void *；尝试这样做将尝试将 a 存储void *在int. 在许多 64 位平台上，这也会溢出（因为void *将是 8 个字节，而int为 4个字节）。制作status一个void *，并停止尝试抛弃这样的编译器错误。他们是有原因的错误。
