Re: git hangs on pthread_join

From: Jeff King <peff@peff.net>
Date: May 28, 2013, 17:51 UTC
Message-ID: <20130528175108.GA21210@sigill.intra.peff.net>
In-Reply-To: <20130523130143.GA6376@pomac.netswarm.net>

On Thu, May 23, 2013 at 03:01:43PM +0200, Ian Kumlien wrote:

Show 11 quoted lines

> git 1.8.2.1 is started by xinetd
> [...]
> I have found "git receive-pack"s that has been running for days/weeks
> without terminating....
> 
> Attaching gdb and doing a trace results in:
> #0  0x0000003261207b35 in pthread_join () from /lib64/libpthread.so.0
> #1  0x00000000004ce58b in finish_async ()
> #2  0x000000000045744b in cmd_receive_pack ()
> #3  0x0000000000404851 in handle_internal_command ()
> #4  0x0000000000404c9d in main ()

I recently fixed a deadlock that could happen in receive-pack when clients hung up before sending a valid pack header. The fix is commit 49ecfa1, and it's in git v1.8.2.2.

The stack trace for the deadlock fixed by 49ecfa1 would have unpack_with_sideband between #1 and #2 above, but it is entirely possible that it is simply inlined in your build of git, depending on the -O level of your build (it is a static function that is only called from one place). So it seems likely that it is the culprit.

-Peff