bug#71094: [PATCH] Prefer to run find and grep in parallel in rgrep

[Manuel Giraud via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Dmitry Gutov <dmitry@gutov.dev> writes:

> On 23/05/2024 07:46, Eli Zaretskii wrote:
>>> From: Manuel Giraud<manuel@ledu-giraud.fr>
>>> Cc:dmitry@gutov.dev,sbaugh@janestreet.com,71094@debbugs.gnu.org,
>>>    rgm@gnu.org
>>> Date: Wed, 22 May 2024 21:15:02 +0200
>>>
>>> Eli Zaretskii<eliz@gnu.org>  writes:
>>>
>>> [...]
>>>
>>>> Thanks, but we need the timings of the corresponding Emacs commands,
>>>> not the commands run from the shell prompt.
>>> Ok.  What are those commands and how to timed them?
>> It's rgrep, AFAIU, according to the original report in this bug's
>> discussion.  Dmitry, would you please show Manual the commands you
>> were running in your benchmarks?
>
> 1. Visit a directory with a fair number of files.
> 2. M-x rgrep, enter some odd regexp like "asdfasf@!#!" and "*" for the
> files wildcard.
> 3. Perform the search. Look at the end of the *grep* output, it will
> say something like "duration: 4.52 s". Note the number.

Thanks.  Here is what I get first without and then with the patch after
cache warming on both runs:

--8<---------------cut here---------------start------------->8---
-*- mode: grep; default-directory: "/usr/src/" -*-
Grep started at Fri May 24 19:04:44

find -H . -type d \( -path \*/SCCS -o -path \*/RCS -o -path \*/CVS -o -path \*/MCVS -o -path \*/.src -o -path \*/.svn -o -path \*/.git -o -path \*/.hg -o -path \*/.bzr -o -path \*/_MTN -o -path \*/_darcs -o -path \*/\{arch\} \) -prune -o \! -type d \( -name .\#\* -o -name \*.o -o -name \*\~ -o -name \*.bin -o -name \*.lbin -o -name \*.so -o -name \*.a -o -name \*.ln -o -name \*.blg -o -name \*.bbl -o -name \*.elc -o -name \*.lof -o -name \*.glo -o -name \*.idx -o -name \*.lot -o -name \*.fmt -o -name \*.tfm -o -name \*.class -o -name \*.fas -o -name \*.lib -o -name \*.mem -o -name \*.x86f -o -name \*.sparcf -o -name \*.dfsl -o -name \*.pfsl -o -name \*.d64fsl -o -name \*.p64fsl -o -name \*.lx64fsl -o -name \*.lx32fsl -o -name \*.dx64fsl -o -name \*.dx32fsl -o -name \*.fx64fsl -o -name \*.f
 x32fsl -o -name \*.sx64fsl -o -name \*.sx32fsl -o -name \*.wx64fsl -o -name \*.wx32fsl -o -name \*.fasl -o -name \*.ufsl -o -name \*.fsl -o -name \*.dxl -o -name \*.lo -o -name \*.la -o -name \*.gmo -o -name \*.mo -o -name \*.toc -o -name \*.aux -o -name \*.cp -o -name \*.fn -o -name \*.ky -o -name \*.pg -o -name \*.tp -o -name \*.vr -o -name \*.cps -o -name \*.fns -o -name \*.kys -o -name \*.pgs -o -name \*.tps -o -name \*.vrs -o -name \*.pyc -o -name \*.pyo \) -prune -o  -type f \( -name \* -o -name .\* \) -exec grep -i -nH --null -e asdfasf\@\!\#\! \{\} +

Grep finished with no matches found at Fri May 24 19:04:54, duration 10.2 s
--8<---------------cut here---------------end--------------->8---

--8<---------------cut here---------------start------------->8---
-*- mode: grep; default-directory: "/usr/src/" -*-
Grep started at Fri May 24 19:37:28

find -H . -type d \( -path \*/SCCS -o -path \*/RCS -o -path \*/CVS -o -path \*/MCVS -o -path \*/.src -o -path \*/.svn -o -path \*/.git -o -path \*/.hg -o -path \*/.bzr -o -path \*/_MTN -o -path \*/_darcs -o -path \*/\{arch\} \) -prune -o \! -type d \( -name .\#\* -o -name \*.o -o -name \*\~ -o -name \*.bin -o -name \*.lbin -o -name \*.so -o -name \*.a -o -name \*.ln -o -name \*.blg -o -name \*.bbl -o -name \*.elc -o -name \*.lof -o -name \*.glo -o -name \*.idx -o -name \*.lot -o -name \*.fmt -o -name \*.tfm -o -name \*.class -o -name \*.fas -o -name \*.lib -o -name \*.mem -o -name \*.x86f -o -name \*.sparcf -o -name \*.dfsl -o -name \*.pfsl -o -name \*.d64fsl -o -name \*.p64fsl -o -name \*.lx64fsl -o -name \*.lx32fsl -o -name \*.dx64fsl -o -name \*.dx32fsl -o -name \*.fx64fsl -o -name \*.f
 x32fsl -o -name \*.sx64fsl -o -name \*.sx32fsl -o -name \*.wx64fsl -o -name \*.wx32fsl -o -name \*.fasl -o -name \*.ufsl -o -name \*.fsl -o -name \*.dxl -o -name \*.lo -o -name \*.la -o -name \*.gmo -o -name \*.mo -o -name \*.toc -o -name \*.aux -o -name \*.cp -o -name \*.fn -o -name \*.ky -o -name \*.pg -o -name \*.tp -o -name \*.vr -o -name \*.cps -o -name \*.fns -o -name \*.kys -o -name \*.pgs -o -name \*.tps -o -name \*.vrs -o -name \*.pyc -o -name \*.pyo \) -prune -o  -type f \( -name \* -o -name .\* \) -print0 | "xargs" -0 grep -i -nH --null -e asdfasf\@\!\#\!

Grep finished with no matches found at Fri May 24 19:37:37, duration 9.01 s
--8<---------------cut here---------------end--------------->8---
-- 
Manuel Giraud