From: Eli Zaretskii <eliz@gnu.org>
To: esr@thyrsus.com
Cc: emacs-devel@gnu.org
Subject: Re: Insight into the mystery hangs
Date: Mon, 12 Feb 2024 21:22:15 +0200 [thread overview]
Message-ID: <86le7pqyhk.fsf@gnu.org> (raw)
In-Reply-To: <ZcpiyJVd6iNFpg7X@thyrsus.com> (esr@thyrsus.com)
> Date: Mon, 12 Feb 2024 13:26:16 -0500
> From: "Eric S. Raymond" <esr@thyrsus.com>
> Cc: emacs-devel@gnu.org
>
> Eli Zaretskii <eliz@gnu.org>:
> > Isn't that call issued from the mode-line display? If so, that is
> > done from redisplay, and redisplay cannot enter debugger, so it
> > catches all errors. If you want to produce Lisp backtraces from Lisp
> > code called by redisplay, you need to use the facilities documented in
> > the node "Debugging Redisplay" in the ELisp Reference manual.
>
> 1. Thinking about it, I can see why redisplay can't be allowed to enter
> the debugger. Infinite regress...
>
> 2. I don't know if that subprocess is called from the modeline
> code. Probably, but I'd have to dig into vc.el to check. I won't have
> time for that for a few days yet.
>
> 3. Assuming that it is called from the modeline code, the question
> shifts from "Why did I have so much trouble generating a debug trace?"
> to "How could I get one at all"?" There's some kind of timing issue,
> I think.
If you eventually can get Emacs into producing a backtrace, the
facilities described in the node "Debugging Redisplay", mentioned
above, should allow you to have it saved in a special buffer that you
can then examine.
> ...this directs my attention to the fact that that Emacs makes it
> generally difficult to notice and diagnose ill-behaved subprocesses,
> wuth problems behind the mode-line being the extreme case. Alas, I
> don't know what to do about this other than windmill my arms at the
> dev group.
Not sure I understand what kind of features would you like to have to
make this easier. To detect the fact that a sub-process takes most of
the time you could use profiler.el -- the profile should show that a
large portion of time is spent inside call-process or its ilk.
Alternatively, you could use 'top' or a similar tool to see what the
Emacs process and its subprocesses are doing.
next prev parent reply other threads:[~2024-02-12 19:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-11 21:37 Insight into the mystery hangs Eric S. Raymond
2024-02-12 12:38 ` Alan Mackenzie
2024-02-12 12:52 ` Eli Zaretskii
2024-02-12 18:26 ` Eric S. Raymond
2024-02-12 19:22 ` Eli Zaretskii [this message]
2024-02-13 7:52 ` Kévin Le Gouguec
2024-02-13 12:56 ` Eli Zaretskii
2024-02-13 23:05 ` Kévin Le Gouguec
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