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From: Junio C Hamano <gitster@pobox.com>
To: "SZEDER Gábor" <szeder.dev@gmail.com>
Cc: git@vger.kernel.org,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	Jeff King <peff@peff.net>, Luke Diamand <luke@diamand.org>,
	Lars Schneider <larsxschneider@gmail.com>
Subject: Re: [PATCH 02/11] t/lib-git-daemon: make sure to kill the 'git-daemon' process
Date: Thu, 14 Mar 2019 11:35:22 +0900	[thread overview]
Message-ID: <xmqqpnqub2tx.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <20190313122419.2210-3-szeder.dev@gmail.com> ("SZEDER Gábor"'s message of "Wed, 13 Mar 2019 13:24:10 +0100")

SZEDER Gábor <szeder.dev@gmail.com> writes:

> After 'start_git_daemon' starts 'git daemon' (note the space in the
> middle) in the background, it saves the background process' PID, so
> the daemon can be stopped at the end of the test script.  However,
> 'git-daemon' is not a builtin but a dashed external command, which
> means that the dashless 'git daemon' executes the dashed 'git-daemon'
> command, and, consequently, the PID recorded is not the PID of the
> "real" daemon process, but that of the main 'git' wrapper.

Hmph.  execv_dashed_external() does not quite execv() but uses
run_command() and waits, which is the source of this issue.  It
feels almost possible to work it around by actually exec'ing,
though.

	/*
	 * If we fail because the command is not found, it is
	 * OK to return. Otherwise, we just pass along the status code,
	 * or our usual generic code if we were not even able to exec
	 * the program.
	 */
	status = run_command(&cmd);
	if (status >= 0)
		exit(status);
	else if (errno != ENOENT)
		exit(128);

would become

	... prepare args from cmd ...
	execv(...);
	if (errno != ENOENT)
		exit(128);

and if exec succeeds, the whole process will exit with the status of
dashed command, failing to exec for reasons other than ENOENT will
exit with 128 and ENOENT will continue returning.

> Now, if a
> test script involving 'git daemon' is interrupted by ctrl-C, then only
> the main 'git' process is stopped, but the real daemon process tends
> to survive somehow, and keeps on running in the background
> indefinitely, keeping the daemon's port to itself, and thus preventing
> subsequent runs of the same test script.
>
> Work this around by running 'git daemon' with the '--pidfile=...'
> option to save the PID of the real daemon process, and kill that
> process in 'stop_git_daemon' as well.

OK, so for the purpose of waiting and monitoring, we still use the
pid of the git potty that is running and waiting for the daemon, but
we'll send another signal to kill the daemon off.  Makes sense.

  reply	other threads:[~2019-03-14  2:35 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-13 12:24 [PATCH 00/11] tests: introduce 'test_atexit' SZEDER Gábor
2019-03-13 12:24 ` [PATCH 01/11] test-lib: fix interrupt handling with 'dash' and '--verbose-log -x' SZEDER Gábor
2019-03-14  2:18   ` Junio C Hamano
2019-03-14 14:50     ` SZEDER Gábor
2019-03-13 12:24 ` [PATCH 02/11] t/lib-git-daemon: make sure to kill the 'git-daemon' process SZEDER Gábor
2019-03-14  2:35   ` Junio C Hamano [this message]
2019-03-13 12:24 ` [PATCH 03/11] test-lib: introduce 'test_atexit' SZEDER Gábor
2019-03-14  3:21   ` Junio C Hamano
2019-03-14 17:40     ` SZEDER Gábor
2019-03-18  1:50       ` Junio C Hamano
2019-03-13 12:24 ` [PATCH 04/11] git-daemon: use 'test_atexit` to stop 'git-daemon' SZEDER Gábor
2019-03-13 12:24 ` [PATCH 05/11] tests: use 'test_atexit' to stop httpd SZEDER Gábor
2019-03-14  3:28   ` Junio C Hamano
2019-03-14  4:34     ` Junio C Hamano
2019-03-14 15:19     ` SZEDER Gábor
2019-03-13 12:24 ` [PATCH 06/11] t0301-credential-cache: use 'test_atexit' to stop the credentials helper SZEDER Gábor
2019-03-13 12:24 ` [PATCH 07/11] git p4 test: use 'test_atexit' to kill p4d and the watchdog process SZEDER Gábor
2019-03-13 12:24 ` [PATCH 08/11] git p4 test: clean up the p4d cleanup functions SZEDER Gábor
2019-03-13 12:24 ` [PATCH 09/11] git p4 test: simplify timeout handling SZEDER Gábor
2019-03-13 12:24 ` [PATCH 10/11] git p4 test: disable '-x' tracing in the p4d watchdog loop SZEDER Gábor
2019-03-13 12:24 ` [PATCH 11/11] t9811-git-p4-label-import: fix pipeline negation SZEDER Gábor

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