How to Restart a Crashed Thread

Question

I'm trying to wait on a thread and restart it if it crashes.

It crashes on the part inside of the if statement. (If I take that out and replace it with a Sleep and then kill the thread inside Process Explorer I do not get any error (but also the thread does not restart). The error I get is an exception due to a stack overflow in ws2_32.dll . I tried calling the current function inside of the function to see if maybe it would work after having the VirtualAlloc() , memcpy() and what not done over again but I got the same error upon attempting to restart the thread.

I noticed though in Procexp that the new (restarted) thread actually ran for a little bit until the program crashed.

HANDLE theadHandle = CreateThread(NULL, 0, LPTHREAD_START_ROUTINE(code), NULL, 0, NULL);

while (true) {
    ...

    BOOL state = WaitForSingleObject(threadHandle, 0); // Checks if the the thread has died and if so restarts it
    if (state == WAIT_OBJECT_0) {
    threadHandle = CreateThread(NULL, 0, LPTHREAD_START_ROUTINE(code), NULL, 0, NULL);
    }
}

I'm expecting the thread restarts as if nothing ever happened.

Thank you for your time.

Answer 1

This approach won't work -- once the memory space of your process is corrupted (as it must be if a thread is crashing), trying to get useful behavior out of your program is a fool's errand. Even if you think you've got it working, sooner or later you'll find out that it doesn't work reliably (eg it only crashes on certain hardware, or under certain conditions).

A better approach is to debug your code so that it never crashes in the first place -- that's the only way to make your program reliable and efficient.

If for some reason you can't do that, a (not very good) work-around would be to launch the buggy code inside a child process instead of in a thread -- that way, at least when the child process corrupts itself, your main process will be protected (and you can then safely start a new child process if you want to). However, this is only a hack work-around; the proper fix is to make sure the crash doesn't happen in the first place, by making sure the code isn't buggy.