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bug#25279: 26.0.50; Slowdown/crash on certain characters
From: |
Eli Zaretskii |
Subject: |
bug#25279: 26.0.50; Slowdown/crash on certain characters |
Date: |
Tue, 27 Dec 2016 09:21:46 +0200 |
> From: Richard Copley <rcopley@gmail.com>
> Date: Mon, 26 Dec 2016 21:21:57 +0000
> Cc: 25279@debbugs.gnu.org
>
> > A crash shouldn't happen in any case, so if you can show a recipe and
> > a backtrace, maybe this could be fixed.
> >
> > Thanks.
>
> Reproducing the slowness and high CPU consumption is easy.
>
> The "crash" I referred to is probably better termed a "hang" (as
> far as I can see an indefinite one), sorry. I don't know a simple
> recipe, but if you use Emacs in this state for long enough, it
> usually hangs eventually.
Is it a hang, or just some long and very busy loop? E.g., if you set
garbage-collection-messages to a non-nil value, do you see periodic
announcements of GC during the "hang"? And if you go for a coffee,
does Emacs eventually recover and starts responding again? What if
you type M-< or M-> to force the problematic characters out of the
displayed portion of the buffer -- does Emacs recover then?
> Recipe:
> Uninstall Symbola (but perhaps other font changes are required).
It isn't easy to uninstall fonts from a running system, because they
are usually in use by some application. So reproducing this will be
hard for me, as I have Symbola installed everywhere. I will try to
find such a system, but no promises.
> Below are C call stacks obtained from a hung emacs process
> by attaching gdb to it.
Is it possible for you to try to figure out what is the looping stack
frame, by following the advice in etc/DEBUG, under "If the symptom of
the bug is that Emacs fails to respond"?
> Possibly a clue:
> While I had the hung emacs process stopped in GDB I started a
> new Emacs process to edit this email and the new Emacs was
> also horribly slow! When I killed the process in the debugger,
> the new Emacs recovered to normal speed.
Attaching a debugger to Emacs built from the master branch causes such
problems due to the low-level keyboard hook in Emacs. (We avoid that
problem when Emacs is started from GDB to begin with.) So I don't
think this is relevant to the issue at hand.
Thanks.
- bug#25279: 26.0.50; Slowdown/crash on certain characters, Richard Copley, 2016/12/26
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- bug#25279: 26.0.50; Slowdown/crash on certain characters, Richard Copley, 2016/12/27
- bug#25279: 26.0.50; Slowdown/crash on certain characters, Eli Zaretskii, 2016/12/27
- bug#25279: 26.0.50; Slowdown/crash on certain characters, Richard Copley, 2016/12/27
- bug#25279: 26.0.50; Slowdown/crash on certain characters, Richard Copley, 2016/12/27