From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Philipp Stephani Newsgroups: gmane.emacs.bugs Subject: bug#33839: 26.1.90; Emacs occasionally fails to receive asynchronous subprocess output in batch mode Date: Tue, 25 Dec 2018 17:41:17 +0100 Message-ID: References: <835zvk9skp.fsf@gnu.org> <83o99c89qg.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: blaine.gmane.org 1545756011 7567 195.159.176.226 (25 Dec 2018 16:40:11 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 25 Dec 2018 16:40:11 +0000 (UTC) Cc: 33839@debbugs.gnu.org To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Tue Dec 25 17:40:07 2018 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1gbpkU-0001qP-O2 for geb-bug-gnu-emacs@m.gmane.org; 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Tue, 25 Dec 2018 08:41:28 -0800 (PST) In-Reply-To: <83o99c89qg.fsf@gnu.org> X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 208.118.235.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.org gmane.emacs.bugs:153830 Archived-At: Am So., 23. Dez. 2018 um 17:54 Uhr schrieb Eli Zaretskii : > > > From: Philipp Stephani > > 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 : > > > > > > > From: Philipp > > > > 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? Because it seemed logical to do so: while the process is running, wait for process output. I don't think the manual states that output can arrive after the process has finished, but if that's the case, then it should do so. > What happens if you do that unconditionally? You mean, without a while loop? It works in this specific case, but doesn't work in other cases, e.g. when a timer runs while the process is still running. To make this work reliably, a loop is required because there's no guarantee that accept-process-output returns only when the process has finished.