bug#51110: Native-comp leaks fds open on /dev/ptmx

[Andrea Corallo <akrl@sdf.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Andrea Corallo <akrl@sdf.org>
>> Cc: Stephen Gildea <stepheng+emacs@gildea.com>, 51110@debbugs.gnu.org
>> Date: Tue, 30 Nov 2021 20:13:07 +0000
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> >> From: Stephen Gildea <stepheng+emacs@gildea.com>
>> >> cc: Andrea Corallo <akrl@sdf.org>, 51110@debbugs.gnu.org
>> >> Date: Sat, 09 Oct 2021 10:01:43 -0700
>> >> 
>> >> Apparently what's happening is that Emacs forks off a child Emacs to do
>> >> the compile and allocates a pty to the child.  These ptys are not
>> >> closed until the compile completes.  It seems Emacs needs to better
>> >> manage the number of simultaneous open ptys.  Or at least be able to
>> >> wait and retry if an open fails.
>> >
>> > Emacs limits the number of these background processes, see
>> > native-comp-async-jobs-number.  (The value zero means use half of the
>> > number of execution units available in the system's processor.)  So we
>> > generally shouldn't have more than that number of open pipes at any
>> > given time.  For the obvious reasons they cannot be closed until the
>> > sub-process exits.
>> 
>> Is there any action we need/can take on this bug?
>
> I don't think there's anything we _can_ do here, and I tried to
> explain why.

I agree, I don't think we really want support `invocation-name'
modifications at runtime.

Shall we close this bug?

  Andrea