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From: Jeff King <peff@peff.net>
To: Derrick Stolee <stolee@gmail.com>
Cc: "SZEDER Gábor" <szeder.dev@gmail.com>,
	"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>,
	git@vger.kernel.org, "Junio C Hamano" <gitster@pobox.com>,
	"Derrick Stolee" <dstolee@microsoft.com>
Subject: Re: [PATCH 1/1] upload-pack: fix race condition in error messages
Date: Thu, 29 Aug 2019 10:38:05 -0400	[thread overview]
Message-ID: <20190829143805.GB1746@sigill.intra.peff.net> (raw)
In-Reply-To: <131dfa37-0f65-f0c3-6f30-5b6eca12d9c0@gmail.com>

On Thu, Aug 29, 2019 at 10:27:16AM -0400, Derrick Stolee wrote:

> > I don't think we should need such a call. For one thing, if it were
> > necessary, that would mean we're not writing out the packet at all. But
> > your whole problem is that we're writing the message twice, one of which
> > comes from the packet.
> 
> The problem the flush() was trying to solve was the new "Broken pipe" error,
> which I had assumed was due to a communication race. (Looking at the message
> more closely now, I see that Szeder was able to repro this broken pipe both
> with and without my change. I am still unable to repro the broken pipe.)

I think the broken pipe is coming the _other_ way. We do send the packet
from the server to the client, but since the client is still writing
when the server has hung up, we get a write error instead of seeing the
error packet.

So any fixes there have to happen on the client side. I am still
confused about why the client is writing in this case, per the argument
in 014ade7484 (upload-pack: send ERR packet for non-tip objects,
2019-04-13). It would be nice to use GIT_TRACE_PACKET to see what it's
trying to write, but I still haven't been able to reproduce the issue.

-Peff

  reply	other threads:[~2019-08-29 14:38 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-28  1:43 [PATCH 0/1] upload-pack: fix race condition in t5516 Derrick Stolee via GitGitGadget
2019-08-28  1:43 ` [PATCH 1/1] upload-pack: fix race condition in error messages Derrick Stolee via GitGitGadget
2019-08-28  9:34   ` SZEDER Gábor
2019-08-28 14:54     ` Jeff King
2019-08-28 15:39       ` Jeff King
2019-08-28 16:15         ` SZEDER Gábor
2019-08-29 12:58           ` Derrick Stolee
2019-08-29 14:13             ` Jeff King
2019-08-29 14:27               ` Derrick Stolee
2019-08-29 14:38                 ` Jeff King [this message]
2019-08-29 21:58                   ` SZEDER Gábor
2019-08-29 22:06                     ` SZEDER Gábor
2019-08-30 12:10                       ` SZEDER Gábor
2019-09-04  5:04                         ` Jeff King
2019-09-10 12:08                           ` SZEDER Gábor

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