bug#20935: sleep-for wakes prematurely due to process output

bug#20935: sleep-for wakes prematurely due to process output

[Francis Litterio]

On Windows, using the latest sources, function sleep-for is woken
prematurely by process (or network connection) output.  I'm not sure if
this also happens on UNIX, but function wait_reading_process_output in
process.c seems to be written to return prematurely when process output
is received.  Function wait_reading_process_output is used by sleep-for
to implement the wait.

To reproduce:

1. Launch Emacs with: runemacs.exe -Q

2. In buffer *scratch*, evaluate this form:

   (progn
     (start-process-shell-command "foo" "*scratch*" "sh -c 'sleep 5; echo hello; sleep 5'")
     (sleep-for 30)
     (insert "Woken from sleep-for!\n"))

3. Observe the text "Woken from sleep-for!" inserted after just 5 seconds
   instead of the expected 30 seconds.

I found this, because calls to sleep-for were not sleeping for the expected
duration when ERC was connected to an IRC server sending regular output over the
network connection.
--
Fran Litterio
flitterio@gmail.com


In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
 of 2015-06-22 on PUPPY
Repository revision: 567bf811dc83d4e2a770f602fc70df0874aa02e4
Windowing system distributor `Microsoft Corp.', version 6.1.7601
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bug#20935: sleep-for wakes prematurely due to process output

[Glenn Morris]

Francis Litterio wrote:

> On Windows, using the latest sources, function sleep-for is woken
> prematurely by process (or network connection) output.  I'm not sure if
> this also happens on UNIX,

Yes, it's the unaddressed http://debbugs.gnu.org/15990 .

bug#20935: sleep-for wakes prematurely due to process output

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Date: Mon, 29 Jun 2015 23:41:18 -0400
> Cc: 20935@debbugs.gnu.org
> 
> Francis Litterio wrote:
> 
> > On Windows, using the latest sources, function sleep-for is woken
> > prematurely by process (or network connection) output.  I'm not sure if
> > this also happens on UNIX,
> 
> Yes, it's the unaddressed http://debbugs.gnu.org/15990 .

Sorry, I completely forgot about that problem (it was still in my
queue).

Now fixed in commit 3bea77f.