cpp simple thread program crashes at exit

Question

I'm trying to understand how to work with threads and this simple code crashes with this error:

the code:

#include <iostream>
#include <thread>
#include <chrono>

using namespace std;

void thread1()
{
    while (true)
    {
        cout << this_thread::get_id() << endl;
    }
}

void main()
{
    thread t1(thread1);
    thread t2(thread1);

    this_thread::sleep_for(chrono::seconds(1));

    t1.detach();
    t2.detach();
}

can someone please explain why it crashes after the detaches and how to fix this?

Informally, all (non shared) resouces shoud be reclaimed by the OS when your program exit. But in this case, there are still some runing threads, which makes the OS mad. — felix, Feb 11 '17 at 18:08
i want to eventually write a multithread server so i have to learn how to use these commands — Guy Shilman, Feb 11 '17 at 18:09
You can use a singleton class to manage all those long-runing threads, and inform them and join them on ending of the service. — felix, Feb 11 '17 at 18:13

score 1 · Answer 1 · answered Feb 11 '17 at 18:06

The reason why you get an error is accessing CRT (C++ Runtime Library) after its deinitialization.

The worker threads use CRT by accessing std::cout. When the main thread leaves main function, the CRT library is unloading, but the worker threads are still trying to use it. Likely, there is a runtime check for it so you get a error message instead of just program crash.

It is better not to use detach method and be sure that all the threads you spawned are finished execution at program exit.

cpp simple thread program crashes at exit

1 Answers1