From: Kim Gybels <kgybels@infogroep.be>
To: Junio C Hamano <gitster@pobox.com>
Cc: Johannes Schindelin <Johannes.Schindelin@gmx.de>,
git@vger.kernel.org, Jeff King <peff@peff.net>
Subject: Re: [PATCH 1/2] daemon: use timeout for uninterruptible poll
Date: Thu, 19 Apr 2018 23:33:22 +0200 [thread overview]
Message-ID: <20180419213322.GA19500@infogroep.be> (raw)
In-Reply-To: <xmqqy3hkfais.fsf@gitster-ct.c.googlers.com>
On (19/04/18 06:51), Junio C Hamano wrote:
> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
> > In other words, you scolded Kim for something that this patch did not
> > introduce, but which was already there.
I didn't feel scolded, just Junio raising a concern about maintainability of
the code.
> > Unless I am misunderstanding violently what you say, that is, in which
> > case I would like to ask for a clarification why this patch (which does
> > not change a thing unless NO_POLL is defined!) must be rejected, and while
> > at it, I would like to ask you how introducing a layer of indirection with
> > a full new function that is at least moderately misleading (as it would be
> > named xpoll() despite your desire that it should do things that poll()
> > does *not* do) would be preferable to this here patch that changes but a
> > few lines to introduce a regular heartbeat check for platforms that
>
> Our xwrite() and other xfoo() are to "fix" undesirable aspect of the
> underlying pure POSIX API to make it more suitable for our codebase.
> When pure POSIX poll() that requires the implementing or emulating
> platform pays attention to the children being waited on is not
> appropriate for the codepath we are using (i.e. the place where the
> patch is touching), it would be in line to introduce a "fixed" API
> that allows us to pass that information, so that we can build on top
> of that abstraction that is *not* pure POSIX abstraction, no? After
> all, you are the one who constantly whine that Git is implemented on
> POSIX API and it is inconvenient for other platforms.
There is another issue with the existing code that this new "xpoll" will need
to take into account. If a SIGCHLD arrives between the call to
check_dead_children and poll, the poll will not be interupted by it, resulting
in the child not being reaped until another child terminates or a client
connects. Currently, the effect is just a zombie process for a longer time,
however, the proposed patch (daemon: graceful shutdown of client connection)
relies on the cleanup to close the client connection.
When I have time, I will reroll including a change to ppoll.
-Kim
next prev parent reply other threads:[~2018-04-19 21:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-12 21:07 [PATCH 0/2] Fix early EOF with GfW daemon Kim Gybels
2018-04-12 21:07 ` [PATCH 1/2] daemon: use timeout for uninterruptible poll Kim Gybels
2018-04-13 12:36 ` Johannes Schindelin
2018-04-15 17:08 ` Kim Gybels
2018-04-18 21:16 ` Johannes Schindelin
2018-04-15 21:54 ` Junio C Hamano
2018-04-15 22:16 ` Junio C Hamano
2018-04-18 21:07 ` Johannes Schindelin
2018-04-18 21:51 ` Junio C Hamano
2018-04-19 21:33 ` Kim Gybels [this message]
2018-04-19 23:18 ` Junio C Hamano
2018-04-12 21:07 ` [PATCH 2/2] daemon: graceful shutdown of client connection Kim Gybels
2018-04-13 13:03 ` Johannes Schindelin
2018-04-15 20:21 ` Kim Gybels
2018-04-18 21:48 ` Johannes Schindelin
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