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I agree and I would make the switch as soon as possible. The graphite graph
you posted showed that since 6/28 the difference in failure rate is such
that isn't even statistically significant. However, spikes in failure rates
of the unstable job also suggest that you're starting to chase a moving
target, and we know how painful this is from the experience we had when
enabling the neutron full job.

Salvatore



On 8 July 2015 at 20:21, Armando M. <armamig at gmail.com> wrote:

> 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. <armamig at 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 <bpavlovic at 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 <clint at 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?
>>>>
>>>>
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>>>
>>>
>>>
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>>
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