I recently got into trouble with a large backlog. What I found was at some point the backlog got too large for gnocchi to effectivly function. When using ceph list of metric objects is kept in a omap object which normally is a quick and efficient way to store this list. However, at some point the list grows too large for it to be managed by the leveldb which implements the omap k/v store. I finally moved to some ssd’s to get enough iops for leveldb/omap to function. What I’m guessing is that if you are using ceph the increased number of metrics grabbed per pass reduced the number of times a now expensive operation is performed. Indications are that the new bluestore should make omap scale much better but isn’t slated to go stable for a few months with the release of Luminous.
> On Mar 28, 2017, at 2:28 PM, Ionut Biru - Fleio <io...@fleio.com> wrote: > > Hello, > > I do have a cloud under administration, my setup is fairly basic, I have > deployed openstack using Openstack Ansible, currently I'm a Newton and > planning to upgrade on Ocata. > > I'm having a problem with gnocchi metricd falling behind on processing > metrics. > > Gnocchi config: https://paste.xinu.at/f73A/ <https://paste.xinu.at/f73A/> > > In I'm using default workers number(cpu count) the number of "storage/total > number of measures to process" keeps growing, last time I had 300k in queue. > In seems that the tasks are not rescheduled in order to process them all in > time and it processing couples of metrics after they are received from > ceilometer and after that they are kept in queue and I only have 10 compute > nodes with about 70 instances. > > In order to process I had to set up workers to a very high number (100) and > keep restarting metricd in order for them to be processed but this method is > very cpu and memory intensive and luckily I found another method that works > quite well. > > https://git.openstack.org/cgit/openstack/gnocchi/tree/gnocchi/cli.py?h=stable/3.1#n154 > > <https://git.openstack.org/cgit/openstack/gnocchi/tree/gnocchi/cli.py?h=stable/3.1#n154> > > I have modified TASKS_PER_WORKER and BLOCK_SIZE to 400 and now metricd keeps > processing them. > > I'm not sure yet if is a bug or not but my question is, how do you guys scale > gnocchi metricd in order to process a lot of resources and metrics? > > _______________________________________________ > OpenStack-operators mailing list > OpenStack-operators@lists.openstack.org > <mailto:OpenStack-operators@lists.openstack.org> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators > <http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators>
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