Re: [PATCH] t9300-fast-import: don't hang if background fast-import exits too early

From: Junio C Hamano <gitster@pobox.com>
Date: Nov 30, 2019, 21:16 UTC
Message-ID: <xmqqsgm512vl.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20191130104644.17350-1-szeder.dev@gmail.com>

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

Show 19 quoted lines

> +	(
> +		git fast-import $options <&8 >&9 &
> +		echo $! >V.fi.pid
> +		wait $!
> +		echo >&2 "background fast-import terminated too early with exit code $?"
> +		# Un-block the read loop in the main shell process.
> +		echo >&9 UNEXPECTED
> +	) &
> +	echo $! >V.sh.pid
>  	# We don't mind if fast-import has already died by the time the test
>  	# ends.
> -	test_when_finished "
> +	test_when_finished '
>  		exec 8>&-; exec 9>&-;
> -		kill $(cat V.pid) && wait $(cat V.pid)
> -		true"
> +		kill $(cat V.sh.pid) && wait $(cat V.sh.pid)
> +		kill $(cat V.fi.pid) && wait $(cat V.sh.pid)
> +		true'

The original interpolates the PID of the fast-import when "when-finished" program is registered, so it is OK if somebody else removed V.pid file; the new one interpolates when "when-finished" program is run, reading from V.??.pid, so somebody needs to make sure these pid files will stay around. I do not think it is an issue as I suspect we've left it to the global clean-up procedure that removes the trash directory to remove the pid file.

By the way, does the second "kill && wait" wait for the right process?

Show 8 quoted lines

>  background_import_still_running () {
> -	if ! kill -0 "$(cat V.pid)"
> +	if ! kill -0 "$(cat V.fi.pid)"
>  	then
>  		echo >&2 "background fast-import terminated too early"
>  		false
>  	fi
>  }