bug#40023: 26.3; Emacs crashes when creating process if many file handles are in use (e.g., when using ccls)

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Date: Wed, 11 Mar 2020 16:32:14 +0100
> Cc: 40023@debbugs.gnu.org
> 
> >>>>> On Wed, 11 Mar 2020 13:50:22 +0000, Holger Pirk <holger@pirk.name> said:
> 
>     Holger> I have spent some time digging around the code and couldn't quite 
> figure
>     Holger> out the logic behind the `fd < FD_SETSIZE`-assert. I suspect the 
> CCLS
>     Holger> opens files without going through emacs' infrastructure which 
> leads to
>     Holger> high file descriptors which emacs cannot handle. I would say that 
> CCLS
>     Holger> is, in part, to blame but emacs shouldn't simply crash.
> 
> Emacs is limited by the limits of select, which supports a maximum of
> FD_SETSIZE file descriptors, which on macOS is 1024
> 
> At least on macOS, itʼs possible to increase that value to eg 8192 by
> setting FD_SETSIZE, which might alleviate this, but then you'd
> probably run into the 'ulimit -n' maximum, so you'd have to remember
> to increase that.

Wasn't this fixed lately by Yamamoto-san?