bug#48118: 27.1; 28; Only first process receives output with multiple running processes

[Eli Zaretskii]

> Cc: 48118@debbugs.gnu.org
> From: Daniel Mendler <mail@daniel-mendler.de>
> Date: Fri, 30 Apr 2021 16:30:54 +0200
> 
> So you say I should repeatedly stop the current process in the filter
> function in order to allow the other process to take precedence

Yes.

> since the underlying Emacs handling of asynchronous processes is
> unable to read from two processes at once?

No.  The problem is not the _ability_ to read from more than one
subprocess -- the ability does exist.  The problem is that doing so
would run afoul of other scenarios.

> me. What is preventing Emacs from treating multiple processes
> fairly?

I asked elsewhere what you mean by "fairly" in this context.

But the general answer to your question is that Emacs knows nothing
about the processes, their importance, their output rates, and the
respective filter functions.