Hi, Another brief update on the matter:
Failure rate trends [1] are showing that unstable (w/ multiple API workers + pymysql driver) and stable configurations (w/o) are virtually aligned and I am proposing that it is time to drop the unstable infra configuration [2,3] that allowed the team to triage/experiment and get to a solution. I'll watch [1] a little longer before I think it's safe to claim that we're out of the woods. Cheers, Armando [1] http://goo.gl/YM7gUC [2] https://review.openstack.org/#/c/199668/ [3] https://review.openstack.org/#/c/199672/ On 22 June 2015 at 14:10, Armando M. <arma...@gmail.com> wrote: > Hi, > > A brief update on the issue that sparked this thread: > > A little over a week ago, bug [1] was filed. The gist of that was that the > switch to pymysql unveiled a number of latent race conditions that made > Neutron unstable. > > To try and nip these in the bud, the Neutron team filed a number of > patches [2], to create an unstable configuration that would allow them to > troubleshoot and experiment a solution, by still keeping the stability in > check (a preliminary proposal for a fix has been available in [4]). > > The latest failure rate trend is shown in [3]; as you can see, we're still > gathering data, but it seems that the instability gap between the two jobs > (stable vs unstable) has widened, and should give us plenty of data points > to devise a resolution strategy. > > I have documented the most recurrent traces in the bug report [1]. > > Will update once we managed to get the two curves to kiss each other again > and close to a more acceptable failure rate. > > Cheers, > Armando > > [1] https://bugs.launchpad.net/neutron/+bug/1464612 > [2] https://review.openstack.org/#/q/topic:neutron-unstable,n,z > [3] http://goo.gl/YM7gUC > [4] https://review.openstack.org/#/c/191540/ > > > On 12 June 2015 at 11:13, Boris Pavlovic <bpavlo...@mirantis.com> wrote: > >> Sean, >> >> Thanks for quick fix/revert https://review.openstack.org/#/c/191010/ >> This unblocked Rally gates... >> >> Best regards, >> Boris Pavlovic >> >> On Fri, Jun 12, 2015 at 8:56 PM, Clint Byrum <cl...@fewbar.com> wrote: >> >>> Excerpts from Mike Bayer's message of 2015-06-12 09:42:42 -0700: >>> > >>> > On 6/12/15 11:37 AM, Mike Bayer wrote: >>> > > >>> > > >>> > > On 6/11/15 9:32 PM, Eugene Nikanorov wrote: >>> > >> Hi neutrons, >>> > >> >>> > >> I'd like to draw your attention to an issue discovered by rally >>> gate job: >>> > >> >>> http://logs.openstack.org/96/190796/4/check/gate-rally-dsvm-neutron-rally/7a18e43/logs/screen-q-svc.txt.gz?level=TRACE >>> > >> >>> > >> I don't have bandwidth to take a deep look at it, but first >>> > >> impression is that it is some issue with nested transaction support >>> > >> either on sqlalchemy or pymysql side. >>> > >> Also, besides errors with nested transactions, there are a lot of >>> > >> Lock wait timeouts. >>> > >> >>> > >> I think it makes sense to start with reverting the patch that moves >>> > >> to pymysql. >>> > > My immediate reaction is that this is perhaps a concurrency-related >>> > > issue; because PyMySQL is pure python and allows for full blown >>> > > eventlet monkeypatching, I wonder if somehow the same PyMySQL >>> > > connection is being used in multiple contexts. E.g. one greenlet >>> > > starts up a savepoint, using identifier "_3" which is based on a >>> > > counter that is local to the SQLAlchemy Connection, but then another >>> > > greenlet shares that PyMySQL connection somehow with another >>> > > SQLAlchemy Connection that uses the same identifier. >>> > >>> > reading more of the log, it seems the main issue is just that there's a >>> > deadlock on inserting into the securitygroups table. The deadlock on >>> > insert can be because of an index being locked. >>> > >>> > >>> > I'd be curious to know how many greenlets are running concurrently >>> here, >>> > and what the overall transaction looks like within the operation that >>> is >>> > failing here (e.g. does each transaction insert multiple rows into >>> > securitygroups? that would make a deadlock seem more likely). >>> >>> This begs two questions: >>> >>> 1) Are we handling deadlocks with retries? It's important that we do >>> that to be defensive. >>> >>> 2) Are we being careful to sort the table order in any multi-table >>> transactions so that we minimize the chance of deadlocks happening >>> because of any cross table deadlocks? >>> >>> >>> __________________________________________________________________________ >>> OpenStack Development Mailing List (not for usage questions) >>> Unsubscribe: >>> openstack-dev-requ...@lists.openstack.org?subject:unsubscribe >>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >>> >> >> >> __________________________________________________________________________ >> OpenStack Development Mailing List (not for usage questions) >> Unsubscribe: >> openstack-dev-requ...@lists.openstack.org?subject:unsubscribe >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> >> >
__________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
