Re: Hang in Emacs 21.3.50

[Jason Rumney <jasonr@gnu.org>]

"Dhruva Krishnamurthy" <seagull@fastmail.fm> writes:

>  I did some further debugging using MSVC 6.0 debugger. I would like to
>  report another scenerio which causes a similar HANG (infinite loop) in
>  w32fns.c:w32_msg_pump()
> 
> 1. I use Aspell (latest : 05.3-2 I guess)
> 2. When I do "M-x ispell-buffer", it goes to w32fns.c:w32_msg_pump() and
> gets into an infinite loop (GetMessage())

It is normal for the message pump thread to spend most of its time in
GetMessage(), and the loop is intentional. The lisp/redisplay thread
is more interesting in cases where Emacs appears to be hung.

> PS:
> Emacs is multi threaded. Am I right or am I missing something.

On MS Windows, there is the main Lisp thread, a message pump thread
(which simulates asynchronous signals and allow C-g to interrupt the
Lisp thread even when it is performing a blocking operation), and a
thread for each subprocess to handle I/O from that subprocess. The
latter thread normally exits when the subprocess exits, so the
message you see about a thread exiting is probably the thread
handling I/O for aspell, as you guessed.

The question, I think, is why does Emacs appear to hang when aspell
exits unexpectedly.