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Re: master reporting "creating pipe: too many open files"
From: |
Stephen Leake |
Subject: |
Re: master reporting "creating pipe: too many open files" |
Date: |
Sat, 16 Jul 2022 14:43:34 -0700 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (windows-nt) |
Eli Zaretskii <eliz@gnu.org> writes:
>> From: Stephen Leake <stephen_leake@stephe-leake.org>
>> Date: Sat, 16 Jul 2022 09:58:18 -0700
>>
>> I have a custom git front-end that works fine in emacs 28, but in
>> current emacs master it always reports "creating pipe: too many open
>> files" after a commands. Then any subsequent command in emacs that
>> requires a file (such as saving a buffer) also fails.
>>
>> This is on Windows 8.1, emacs built with mingw64.
>>
>> I'm guessing there is some file/process handle that is opened and not
>> closed.
>>
>> I update my local copy of emacs master rarely, so this change happened
>> sometime since Dec 2021; I have not tried to bisect.
>>
>> Attached is some simplified code that shows the problem; it runs a
>> subprocess the same way the git front-end does. To run, load the file,
>> then run M-x dd-test. On my system, master is ok with 10 processes,
>> fails with 100 (I did not bisect further). Emacs 28 is ok forever.
>>
>> Before I submit a bug report, I want to check that there is nothing
>> simple wrong with the code; is it relying on undocumented behaviour in
>> emacs 28, or something similar?
>
> You code starts subprocesses in a loop.
Yes, but it waits for each to complete before starting the next one.
That's why it works fine in Emacs 28.
> Emacs on MS-Windows cannot support more than 30 subprocesses (assuming
> no other process objects, like network connection, exist). That's
> because the pselect emulation is limited to 64 handles, and we use 2
> handles per subprocess.
>
> Is what you see consistent with this limitation?
No. That has not changed between 28 and master.
I did test on Debian; no problems there.
I'll create a bug report.
--
-- Stephe