shouldn't at_thread_exit work on the main thread?

[viboes]

In the following example mycallable1 is not called at exit of the main thread. Shouldn't at_thread_exit work on the main thread?

    #include <boost/thread.hpp>
    #include <iostream>

    struct mycallable1
    {
        void operator()() const {
            std::cout << "mycallable1" << std::endl;
        };
    };
    struct mycallable2
    {
        void operator()() const {
            std::cout << "mycallable2" << std::endl;
        };
    };

    void my_thread() {
        std::cout << "my_thread" << std::endl;
        mycallable1 x;
        boost::this_thread::at_thread_exit(x);
    }

    int main() {
        mycallable2 x;
        boost::this_thread::at_thread_exit(x);

        boost::thread th(my_thread);
        th.join();
        return 0;
    }

Output: my_thread mycallable1

[viboes]

The attached files contains the tests showing the bug and a patch solving the issue. The idea been use atexit for the main thread.

[viboes]

I have no modified nothing for window as I can not check it. Can someone apply the same modifications to the src/win32/thread.cpp file?

[viboes]

Replying to viboes:

The attached files contains the tests showing the bug and a patch solving the issue. The idea been use atexit for the main thread.

I have run the Thread tests and the patch introduce a regression on test_tss.cpp:test_tss. The reason is that the patch do not make a difference between the thread main and native threads created directly with pthread_create. So the patch is not usable. Is there a way to identify the thread main?

[Vladimir Prus]

It's not apparent that this is showstopper bug, nor even regression.

[cowwoc@…]

Hi,

I can confirm that this issue affects Boost 1.40 under Windows. Please fix it for this platform too!

[Anthony Williams]

No, at_thread_exit should not work on the main thread.

If you call exit() then all threads are abruptly terminated without calling their exit handlers.

Returning from main is defined to be equivalent to calling exit(), so all threads (including the main thread) are terminated without calling exit handlers.

On POSIX, if you exit the main thread by calling pthread_exit() then the thread exit handlers should run. Similarly, on Windows you can use ExitThread(). However, I would recommend using atexit or explicit calls, or even just normal destructors, since using pthread_exit() or ExitThread will not run destructors for automatic_objects.