reassign 1079088 emacs
severity 1079088 normal
thanks
El 20/8/24 a las 2:10, Vincent Lefevre escribió:
Package: diffutils
Version: 1:3.10-1
Severity: important
Affects: emacs-gtk
Forwarded: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=72723
I've just reported the following bug upstream:
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When opening a .diff file, GNU Emacs runs "diff -ad" on 2 files
it has built (I suppose that the reason is to get a word diff),
and this can be very slow, even though the original .diff file
is rather simple.
I've attached a slow-diff.tar.xz archive with:
* diff1L52tn0 and diff2U4TVho (files built be GNU Emacs).
* file.diff the original .diff file.
When running "/usr/bin/emacs -Q file.diff.xz", I could see what
takes the whole time with ps or top. Here I could see
diff -ad /tmp/diff1L52tn0 /tmp/diff2U4TVho
As this is slow, I could obtain these files.
On my recent machine, "diff -ad diff1L52tn0 diff2U4TVho" takes
27 seconds.
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Note that Emacs cannot even be interrupted with C-g (this may be
an additional bug in Emacs).
As pointed out by Paul Eggert in bug-diffutils, diff -d
is *inherently* slow. This is documented in the diff --help
output:
-d, --minimal try *hard* to find a smaller set of changes
and also in the texinfo manual:
'-d'
'--minimal'
Change the algorithm perhaps find a smaller set of changes. This
makes 'diff' slower (sometimes much slower).
Since I can't control how emacs calls diff, there is nothing I can
reasonably do on the diffutils packaging side.
Thanks.
