Re: [PATCH] remote-curl: don't hang when a server dies before any output

From: Jeff King <peff@peff.net>
Date: Nov 18, 2016, 17:01 UTC
Message-ID: <20161118170147.g7nbkxpyihwkk6fw@sigill.intra.peff.net>
In-Reply-To: <xmqqzil0tza6.fsf@gitster.mtv.corp.google.com>

On Tue, Nov 15, 2016 at 09:42:57AM -0800, Junio C Hamano wrote:

Show 8 quoted lines

> >> Hmph.  I think I tried David's original under GIT_TEST_LONG and saw
> >> it got stuck; could be the same issue, I guess.
> >
> > It works OK here. I think it is just that the test is really slow (by
> > design).
> 
> Yeah, I think what I recalled was my old attempt to run the
> follow-up "any SHA-1" patch without this one.

Right, that makes sense.

So I don't feel like we have a good patch for the general case yet, and I'm probably not going to get around to implementing it anytime soon. So I'd suggest taking David's original patch (to punt when the response is empty) in the meantime.

It doesn't fix all cases, but if fixes _a_ case, and probably one of the most likely one in practice. I don't think it can cause any regressions. It's a "snooping" solution like mine, but it makes many fewer assumptions about the protocol. We know that an empty response cannot possibly advance fetch-pack further because we won't have sent it any bytes. :)

I do think the commit message could be improved based on the discussion here, though (at the very least to describe the nature of the deadlock, and that we are choosing only one of the possible solutions, and why).

-Peff