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Were the backends (zookeeper, etcd) deployed in a cluster configuration? I
can't quite tell from the doc.

On Fri, Jul 22, 2016 at 12:58 AM, John Schwarz <jschwarz at redhat.com> wrote:

> You're right Joshua.
>
> Tooz HEAD points to 0f4e1198fdcbd6a29d77c67d105d201ed0fbd9e0.
>
> With regards to etcd and zookeeper's versions, they are:
> zookeeper-3.4.5+28-1.cdh4.7.1.p0.13.el6.x86_64,
> etcd-2.2.5-2.el7.0.1.x86_64.
>
> John.
>
> On Thu, Jul 21, 2016 at 8:14 PM, Joshua Harlow <harlowja at fastmail.com>
> wrote:
> > Hi John,
> >
> > Thanks for gathering this info,
> >
> > Do you have the versions of the backend that were used here (particularly
> > relevant for etcd which has a new release pretty frequently).
> >
> > It'd be useful to capture that info also :)
> >
> > John Schwarz wrote:
> >>
> >> Hi everyone,
> >>
> >> Following [1], a few of us sat down during the last day of the Austin
> >> Summit and discussed the possibility of adding formal support for
> >> Tooz, specifically for the locking mechanism it provides. The
> >> conclusion we reached was that benchmarks should be done to show if
> >> and how Tooz affects the normal operation of Neutron (i.e. if locking
> >> a resource using Zookeeper takes 3 seconds, it's not worthwhile at
> >> all).
> >>
> >> We've finally finished the benchmarks and they are available at [2].
> >> They test a specific case: when creating an HA router a lock-free
> >> algorithm is used to assign a vrid to a router (this is later used for
> >> keepalived), and the benchmark specifically checks the effects of
> >> locking that function with either Zookeeper or Etcd, using the no-Tooz
> >> case as a baseline. The locking was checked in 2 different ways - one
> >> which presents no contention (acquire() always succeeds immediately)
> >> and one which presents contentions (acquire() may block until a
> >> similar process for the invoking tenant is complete).
> >>
> >> The benchmarks show that while using Tooz does raise the cost of an
> >> operation, the effects are not as bad as we initially feared. In the
> >> simple, single simultaneous request, using Zookeeper raised the
> >> average time it took to create a router by 1.5% (from 11.811 to 11.988
> >> seconds). On the more-realistic case of 6 simultaneous requests,
> >> Zookeeper raised the cost by 3.74% (from 16.533 to 17.152 seconds).
> >>
> >> It is important to note that the setup itself was overloaded - it was
> >> built on a single baremetal hosting 5 VMs (4 of which were
> >> controllers) and thus we were unable to go further - for example, 10
> >> concurrent requests overloaded the server and caused some race
> >> conditions to appear in the L3 scheduler (bugs will be opened soon),
> >> so for this reason we haven't tested heavier samples and limited
> >> ourselves to 6 simultaneous requests.
> >>
> >> Also important to note that some kind of race condition was noticed in
> >> tooz's etcd driver. We've discussed this with the tooz devs and
> >> provided a patch that is supposed to fix them [3].
> >> Lastly, races in the L3 HA Scheduler were found and we are yet to dig
> >> into them and find out their cause - bugs will be opened for these as
> >> well.
> >>
> >> I've opened the summary [2] for comments so you're welcome to open a
> >> discussion about the results both in the ML and on the doc itself.
> >>
> >> (CC to all those who attended the Austin Summit meeting and other
> >> interested parties)
> >> Happy locking,
> >>
> >> [1]:
> >>
> http://lists.openstack.org/pipermail/openstack-dev/2016-April/093199.html
> >> [2]:
> >>
> https://docs.google.com/document/d/1jdI8gkQKBE0G9koR0nLiW02d5rwyWv_-gAp7yavt4w8
> >> [3]: https://review.openstack.org/#/c/342096/
> >>
> >> --
> >> John Schwarz,
> >> Senior Software Engineer,
> >> Red Hat.
> >>
> >>
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> >
> >
> >
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>
>
> --
> John Schwarz,
> Senior Software Engineer,
> Red Hat.
>
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