Re: What does the error "Process <URL> not running" mean?

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: help-gnu-emacs@gnu.org
> Date: Wed, 09 Feb 2022 09:43:25 +0100
> 
> >>>>> On Tue, 08 Feb 2022 20:35:38 +0200, Eli Zaretskii <eliz@gnu.org> said:
> 
>     >> From: Robert Pluim <rpluim@gmail.com>
>     >> Date: Tue, 08 Feb 2022 17:20:41 +0100
>     >> Cc: Stefan Monnier <monnier@iro.umontreal.ca>
>     >> 
>     >> Iʼd rather someone with the requisite skills and tolerance for Windows
>     >> changed the Emacs select emulation to remove the limit (perhaps by
>     >> using the Gnulib 'select' module).
> 
>     Eli> Why do you think the Gnulib module is free from the same (or similar)
>     Eli> limitation?  Isn't FD_SETSIZE = 64 in winsock2.h?
> 
> It is, but youʼre allowed to set it higher, as far as I know.

Not with the Gnulib emulation, AFAICT, since they call the same API we
call in Emacs, which is limited to waiting on 64 handles.

> Maybe it would be enough to just call winsock `select' from Emacs'
> select emulation, but only for sockets.

That's ugly, complicated (sockets are handles, file descriptors
aren't), and in some use cases will still hit the limit.

These half-measures aren't the kind of a solution I'd consider as good
candidates for replacing the current code.  We should probably use
WSAAsyncSelect for sockets, and/or use several threads, each one
watching 64 handles, to wait on 64*N handles.  _That_ would be worth
it.

>     Eli> Also, the pselect emulation in Emacs also emulates SIGCHLD from
>     Eli> sub-processes, something the Gnulib module does not AFAIR.
> 
> Thatʼs only needed for real sub-processes, not sockets, no?

Yes, but we still need it.

>     Eli> And finally, Gnulib dropped Windows 9X support long ago, so its 
> module
>     Eli> will not run on those old versions (and actually is unlikely to run
>     Eli> even on Windows XP, as they've abandoned that as well).
> 
> At some point we have to stop supporting ancient platforms.

At some point, yes, and the motivation should be more serious than be
able to use internal Windows APIs freely.