[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#66096: High CPU usage, basically runaway emacs with visit to bidi_ca
From: |
ISHIKAWA,chiaki |
Subject: |
bug#66096: High CPU usage, basically runaway emacs with visit to bidi_cache_search on and off? |
Date: |
Wed, 20 Sep 2023 16:09:03 +0900 |
User-agent: |
Mozilla Thunderbird |
On 2023/09/19 20:04, Eli Zaretskii wrote:
Cc: "ishikawa, chiaki" <ishikawa@yk.rim.or.jp>
Date: Tue, 19 Sep 2023 13:12:33 +0900
From: "ISHIKAWA,chiaki" <ishikawa@yk.rim.or.jp>
High CPU usage, basically runaway emacs with visit to bidi_cache_search
on and off?
Hi,
Environment:
OS GNU/Debian Linux X86_64
Emacs version
GNU Emacs 29.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
cairo version 1.16.0) of 2023-08-01
I compiled emacs using gcc.
Has anyone seen emacs 29.1 spending CPU way too high, basically went
into an infinite loop of some sort, and could not be interrupted by
Control-G? Basically it is in a runaway state.
I found that the stacktraces show that bidi_cache_search
and friends are visited now and then. It is not the recursive blowup
probably since the stack depth is quite limited during my observation.
I have experienced this issue this morning. Observing the stack
backtrace by monitoring the runaway emacs using gdb, I was surprised
to see many appearances of bidi_cache_search that were observed from
time to time while I do control-C to stop emacs and monitor
stacktrace, and the continue for a few seconds, and interrupt it again
with control-C. After letting emacs run in this manner for about 5
minutes, I had tp kill emacs. I had to edit the file by a deadline and
could not continue debugging. :-(
At the end is a single stacktrace with bidi_cache_search at the top.
I have seen this occurring multiple times. My hitting control-C to emacs
to enter gdb interaction means that the chance of hitting a particular
stacktrace pattern is small and seeing the same pattern multiple times
means that that pattern happens quite often.
The backtrace shows we were resizing the mini-window, but it doesn't
tell where and why we were looping.
(The bidi_cache_search part is probably a red herring: that function
is indeed called very frequently when Emacs performs display and
layout calculations -- which is not surprising, since that's why the
bidi cache exists: to provide cache hits whenever possible.)
So it is important to have a file and the sequence of commands that
trigger this. Please try to produce such a file and a recipe to
reproduce the problem.
Alternatively, you can use the technique described in etc/DEBUG for
finding where Emacs loops, see there under "If the symptom of the bug
is that Emacs fails to respond". I think even if you do discover
where it loops, we'd need an example file to see why, though.
I have a dozen or so more different stacktraces during gdb monitoring.
If someone wants to see the log, I can post it.
What is the preferred URL where I can paste the whole gdb session?
You can post them here, perhaps compressed. However, if they are all
of the same kind, i.e. start with resize_echo_area_exactly, then I
don't think more backtraces alone will help.
Thanks.
Thank you for your comment.
There seem to be enough variation of the stacktrace patterns.
I am attaching the gdb session file as zipped archive.
As you suggested, it seems Emacs is trying to resize echo area, and is
looping somehow.
resize_echo_area_exactly () seems to be always there.
It could be that it was trying to dump the S-expression that encodes the
latest GC information after each GC.
I have the following code snippet to monitor GC issues on my PC for
quite sometime.
But I have not seen this particular problem before.
The long pause I have seen before was strictly in GC-related routines.
(setq my-gc-statistics (make-vector 30 nil))
;;; The element is
;;; (append (memory-use-counts) (list gc-elapsed gcs-done))
;;; Each time the following function is called, the
;;; elements in the array is shifted toward the end.
;;; Use (message "%S" my-gc-statistics) to force the
;;; recording of my-gc-statistics value in *Messages* buffer for later
analysis.
(defun update-my-gc-statistics ()
(let ((i 28))
(progn
;;; very unlike Lisp
(while (<= 0 i)
(progn (aset my-gc-statistics (+ 1 i) (aref my-gc-statistics i))
(setq i (- i 1) )))
(aset my-gc-statistics 0
(append (memory-use-counts) (list gc-elapsed gcs-done)))
;;; print the latest one last so that I can see the glimpse in the
narrow
;;; output window.
(message "%S\n%S" (current-time-string) (pp (reverse
my-gc-statistics))))))
(setq post-gc-hook 'update-my-gc-statistics)
For example, in one place, I see
#0 0x0000556f1905be9e in string_char_and_length
(length=<synthetic pointer>, p=0x556f20d8a3d8 " 70337 417360
2.323839139 50)\n (99058573 3875 59193441 34949 11084445 70337 417401
2.391973008 51)]\n\"") at
/home/ishikawa/repos/emacs-29.1/src/character.h:375
And that string is probably from (append (memory-use-counts) (list
gc-elapsed gcs-done))
Also I see recursive_edit at the bottom of the stakctrace.
Not sure why. Maybe I was doing some error recovery of Japanese input?
In any case, Emacs should not enter a state that cannot be interrupted
by CONTROL-G for a long time IMHO.
(Or was it that the processing of control-G somehow resulted in the
effort to widen echo area and emacs failed?)
TIA
Chiaki
emacs-cant-be-interrupted-with-control-g.zip
Description: Zip compressed data
- bug#66096: High CPU usage, basically runaway emacs with visit to bidi_cache_search on and off?, ISHIKAWA,chiaki, 2023/09/19
- bug#66096: High CPU usage, basically runaway emacs with visit to bidi_cache_search on and off?, Eli Zaretskii, 2023/09/19
- bug#66096: High CPU usage, basically runaway emacs with visit to bidi_cache_search on and off?,
ISHIKAWA,chiaki <=
- bug#66096: High CPU usage, basically runaway emacs with visit to bidi_cache_search on and off?, ISHIKAWA,chiaki, 2023/09/20
- bug#66096: High CPU usage, basically runaway emacs with visit to bidi_cache_search on and off?, Eli Zaretskii, 2023/09/20
- bug#66096: High CPU usage, basically runaway emacs with visit to bidi_cache_search on and off?, ISHIKAWA,chiaki, 2023/09/20