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bug#33839: 26.1.90; Emacs occasionally fails to receive asynchronous sub
From: |
Eli Zaretskii |
Subject: |
bug#33839: 26.1.90; Emacs occasionally fails to receive asynchronous subprocess output in batch mode |
Date: |
Sun, 23 Dec 2018 18:54:15 +0200 |
> From: Philipp Stephani <p.stephani2@gmail.com>
> Date: Sun, 23 Dec 2018 17:45:31 +0100
> Cc: 33839@debbugs.gnu.org
>
> Am So., 23. Dez. 2018 um 16:22 Uhr schrieb Eli Zaretskii <eliz@gnu.org>:
> >
> > > From: Philipp <p.stephani2@gmail.com>
> > > Date: Sun, 23 Dec 2018 03:28:53 +0100
> > >
> > > (with-temp-buffer
> > > (let ((proc (make-process :name "test"
> > > :command '("bash" "-c" "echo stdout; echo
> > > stderr >&2")
> > > :buffer (current-buffer)
> > > :connection-type 'pipe
> > > :sentinel #'ignore
> > > :noquery t
> > > :coding '(utf-8-unix . utf-8-unix))))
> > > (when (process-live-p proc)
> > > (process-send-eof proc))
> > > (while (process-live-p proc)
> > > (accept-process-output proc))
> > > (cl-assert (equal (buffer-string) "stdout\nstderr\n") :show-args)))
> > >
> > > Then evaluate this form repeatedly. Occasionally the buffer is empty
> > > and the assertion triggers.
> >
> > Isn't there an inherent race condition here?
>
> Maybe? If so, then it should be documented, with an explanation how to
> write this in a race-free manner.
Can you tell why you used the process-live-p condition for calling
accept-process-output? What happens if you do that unconditionally?
bug#33839: 26.1.90; Emacs occasionally fails to receive asynchronous subprocess output in batch mode, Paul Eggert, 2018/12/27