bug#32986: 27.0.50; unexpected delay in while-no-input + accept-process-output

["João Távora" <joaotavora@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: João Távora <joaotavora@gmail.com>
>> Date: Tue, 9 Oct 2018 09:47:58 +0100
>> Cc: 32986@debbugs.gnu.org
>> 
>> A final question: process input is also considered during the
>> sit-for, meaning a filter can throw to an
>> enclosing tag and end it prematurely and immediately, right?
>
> You mean, if the only input is from a subprocess?  No, I don't think
> so.  Do you have evidence to the contrary?

Hi Eli,

Sorry for the delay in my reply.

I meant the following, which appears to do what I want in my testing:

   (joaot/time
    (catch 'done
      (progn (make-process :name "test"
                           :filter (lambda (proc string)
                                     (message "Hey %s just got %s" proc string)
                                     (throw 'done nil))
                           :command '("sh" "-c" "sleep 2 && echo bla"))
             (while (sit-for 30))))) ; Took 02.011 seconds and returned nil

The above result is with C-u C-x C-e and no further keyboard input. If
however I press C-u C-x C-e SPC as in my previous experiments, I get the
expected very small delay.

In other words, subprocess input is considered during a 'sit-for'. It
doesn't end it, but that's OK if catch/throw is used.

I'd just like to confirm that I'm not dealing with an "dirty room"
situation here, to use your metaphor.

João