bug#63132: Bug on Darwin MacOS with 'M-x man RET commandname[ ]'

[Eshel Yaron]

Hi,

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Stefan Monnier <monnier@iro.umontreal.ca>
>> Cc: asocial-hired.0l@icloud.com,  63132@debbugs.gnu.org
>> Date: Mon, 01 May 2023 14:03:40 -0400
>>
>> >> So `M-x man RET 2 SPC TAB` should (hopefully) list all the section
>> >> 2's manpages.
>> > So you are saying the lags here are unavoidable?
>>
>> I don't know.  I don't see any significant lag here.
>
> The OP says it only happens on macOS, not on GNU/Linux.
>
>> But if that's a problem, maybe we should tweak the system so we only
>> fetch the list when there's at least one char after the space (to
>> keep the list shorter)?
>
> Something like that.
>

I can confirm that completion in `M-x man` induces a seconds-long lag on
Mac OS.  I believe that has been the case, for me, for at least a couple
of years.  I often find myself typing out the man page name I'm looking
for in full and avoiding completion because of this.

>> The OP mentions Emacs crashing, which points to another problem than
>> mere lag.

This I cannot confirm or reproduce.  AFAIR I never had Emacs crash while
using `M-x man`.

>> And maybe it depends on the system (or more specifically on what kind of
>> `man` program is installed and how it supports `man -k`; e/g. if
>> there's no prebuilt index and `man -k` scans through all the installed
>> troff pages every time)?
>
> Any macOS users out there who could reproduce and debug this?

On my i9 Ventura MacBook Pro, just running `man -k read > /dev/null`
takes almost 2.5 seconds, it'd seem that's indeed the main cause of this
lag in `M-x man` completion.


-- 
Eshel