我正在尝试接受Integer值，并在程序中创建该数量的线程 . 很奇怪，只能创建第一个线程 . 经过一些跟踪后，它显示pthread_create是导致核心转储的行 .
#include <iostream>
#include <time.h>
#include <pthread.h>
using namespace std;
class Kevin
{
public:
Kevin();
static void* Speak(void* value);
};
Kevin::Kevin()
{
cout << "new instance of Kevin is created\n";
}
void* Kevin::Speak(void* value)
{
cout << "Name: Kevin" << *((int*)value) << "\n" << "Seconds since epoch:" << "\nThread id:" << pthread_self() << endl;
}
int main(int argc, char *argv[])
{
int threadsNumb = atoi(argv[1]);
cout << "number of threads :" << threadsNumb <<endl;
int status;
int i;
pthread_t threads[threadsNumb];
for(i=0;i<threadsNumb;i++)
{
cout << "what is i? " << i << endl;
cout << &threads[i] << i << endl;
cout << "threads" << threads[i] << endl;
cout << "thread Numb" << threadsNumb << endl;
pthread_create(&(threads[i]),NULL,Kevin::Speak,(void *)&i); // this line
pthread_join(threads[i], (void **)&status);
cout << endl;
}
return EXIT_SUCCESS;
}
使用“./a.out 3”运行会输出：
number of threads :3
what is i? 0
0x7fff3600ae400
threads6296496
thread Numb3
Name: Kevin0
Seconds since epoch:
Thread id:1117690176
what is i? 1
0x7fff000000081
Segmentation fault (core dumped)
我尝试将 pthread_t threads[threadsNumb]; 的声明移动到for循环中，它可以运行但它会给我所有相同的Thread ID，这是不需要的 . 知道核心转储可能是什么原因？它也查了一个类似的问题，但我没有重新声明任何内容：pthread_create causing segmentation fault
这是我将pthread join的第二个参数更改为NULL后得到的结果 .
what is i? 0
0x7fffe23e12f00
threads6296496
thread Numb3
Name: Kevin0
Seconds since epoch:
Thread id:1098664256
what is i? 1
0x7fffe23e12f81
threads242525729787
thread Numb3
Name: Kevin1
Seconds since epoch:
Thread id:1098664256
what is i? 2
0x7fffe23e13002
threads47489276644304
thread Numb3
Name: Kevin2
Seconds since epoch:
Thread id:1098664256
为什么Thread ID相同？
1 回答
一个可能的原因可能是你在64位机器上，其中
int是32位但指针是64位 . 这意味着您的pthread_join调用将在为变量status分配的空间之外写入 . 变量i不会被覆盖（在第二个循环中打印的地址暗示与第一个地址有很大不同） .在你的情况下，你实际上没有从线程函数返回任何东西，你也可以传递
NULL作为pthread_join的第二个参数 .