Re: Lots of hangs Windows 10 26.0.91

[Eli Zaretskii <eliz@gnu.org>]

> From: Adam Taylor <mr.adtaylor@gmail.com>
> Date: Wed, 28 Mar 2018 10:18:13 -0400
> 
> I'm looking for ideas on how to debug a fairly common hang I'm getting
> while running emacs 26.0.91 under Windows 10 (I know, that's my first
> problem).
> 
> I've been using mostly magit and elpy (python-mode) stuff when it happens.
> I use desktop-save-mode which I suspected was the culprit until I turned it
> off and the problem still happened.
> 
> What happens is that emacs starts to consume 30-40% of the cpu and starts
> to eat memory at a good clip eventually causing my machine to start to page.
> 
> C-g does not work. I have to kill emacs from the task manager.
> 
> It does not seem to be linked to any particular action I make - sometimes
> I'm just editing the python, sometimes I'm updating the magit status
> window. No rhyme or reason that I can divine.
> 
> My guess is some issue in communicating with a subprocess (magit and elpy
> both work with subprocesses).
> 
> I seem to remember some chatter about subprocess problems in the emacs
> developer mailing list and wasn't sure if this was the same issue.
> 
> I would like to debug this, but since I didn't build the windows emacs, it
> might be really hard to connect it to gdb and see where it has gone south.
> 
> Any help/pointers is greatly appreciated.

Please start by reporting this is a bug, using "M-x report-emacs-bug".
This forum is not the right place to discuss debugging of Emacs
problems.

Given the description of the issue, I'd start by asking whether you
are sure this is a "hang".  Did you leave Emacs alone long enough to
maybe finish whatever it's doing and become responsive again?  How
long did you wait before giving up and killing it?

Next, can you try disabling all or most of your customizations?  E.g.,
how about disabling all the non-default values of variables, and only
leaving the add-on packages that you load?  If that fixes the problem,
then you need to look at the customizations for the possible cause.

Did you try disabling the add-on packages one by one, perhaps some of
them has a bug.

If none of the above gives a clue, start Emacs under GDB, and when
that happens interrupt Emacs with Ctrl-C and show the C-level
backtrace.  The file etc/DEBUG in the distribution sho0uld explain how
to set things up so that Emacs will be interruptible in such
situations when run under GDB.  You will need to install a Windows
port of GDB, of course, which is available from the MSYS2 project.