Crash (double free or corruption) on trying to proxy to localhost

[Stephen Weeks]

Sure!  I've added it to the post on github.  I've slightly edited the log
out of paranoia (replacing a customer ID and auth key).

I can confirm now that I ran this proxy with the upstreamfair module
overnight and it didn't crash at all.  I can't get it to preferentially
serve to localhost, though, as it doesn't support 'backup' as a server
attribute, and doesn't seem to really use the weights, so that's suboptimal.

Anything else I can add to help troubleshooting this?  Anything you'd like
from the core dump?

On Mon, May 2, 2011 at 2:04 PM, Maxim Dounin <mdounin at mdounin.ru> wrote:

> Hello!
>
> On Sun, May 01, 2011 at 05:54:17PM -0700, Stephen Weeks wrote:
>
> > I've currently got a pool of systems running nginx proxying to a pool of
> > systems running apache.  I'm trying to move to running nginx locally on
> the
> > apache hosts instead of separate systems to avoid the extra network hop,
> > make more-efficient use of resources, and enable some future development
> > (including migrating to running our application on nginx via fastcgi
> instead
> > of apache, ideally).  we've currently got some significant architecture
> > built up around apache, so converting right now is uncomfortable.
> >
> > Ideally, I'd like nginx to just serve from localhost, but fail over to
> the
> > rest of the pool when localhost in unavailable, so in my upstream I have
> > every server except for localhost set as 'backup'.  I'm otherwise running
> > identical configurations of apache and nginx on a single system together
> as
> > used in the rest of the two pools.  This works exactly as expected,
> except
> > that I get a few crashes of nginx workers every minute.  This only
> happens
> > when proxying to the local system.  If I proxy anywhere else, it works
> > fine.  Other proxies can serve from this system without trouble.  I see
> this
> > same behaviour on other hosts when I build them the same way, so it's not
> an
> > error with the host.  I see this crash on 0.7.65, 0.8.54, and 1.0.0,
> running
> > on Ubuntu 10.04 LTS.  I see this crash whether I'm connecting to
> 127.0.0.1
> > or the host's local IP.  I see this crash whether I'm listening on *:80
> or
> > <public ip>:80.  I see this crash whether I'm connecting to :80 or
> running
> > apache on a different port and connecting to :81.  I see this crash
> whether
> > I'm running ubuntu's "nginx-light" configuration, or their "nginx-full"
> > configuration.  I see no errors logged from apache.
> >
> > 1) I'd really love to make this work, so if there's anything else I can
> try,
> > any additional debugging information I can give, I'd appreciate it.
> > 2) Nginx has been very useful to me so far, so I thought you'd appreciate
> a
> > bug report.
> >
> > Posted on github, I have a problem description, section of a debug log,
> my
> > (slightly edited: flattened includes and stripped an IP) nginx.conf, a
> gdb
> > backtrace, and some additional information I was asked for when looking
> for
> > help on IRC.  This is everything I've been able to come up with that
> sounds
> > plausibly relevant.
> >
> > https://gist.github.com/1574dbaf3a3dcda920a2
> >
> > Any help?
>
> Could you please provide:
>
> 1. nginx -V output
>
> 2. Full debug log for '*60' connection (the one which triggered
> abort in glibc), the one you provided contatins only last part of
> the connection in question.  Running grep -F ' 27772#0: *60 ' on
> original debug log should produce something useable.
>
> Maxim Dounin
>
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>
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