> In my case, exception occured in separate thread between the begginig
> of the thread and starting loop.
> 
> Main thread has a code that correctly stops that separate thread. It
> just calls loop_thread.server.server_close() and after that, calls
> loop_thread.join()
> 
> So, if program termination required, but loop was not started,
> deadlock occur.

Sorry, can you post a snippet reproducing the issue? It will make it
clearer for me to understand it.