Hi Eric, thanks, that's very useful reading. I suspect the root issue is the same, as this isn't specific to Ironic per se, but rather is linked to a high # of hypervisors managed by one compute service. In our case, Placement was able to keep up just fine (though raising this job interval also lowered the number of requests to Placement significantly.) My suspicion was that it was less about load on Placement, and more about this lock contention. I will have to try pulling in these patches to test that.

Cheers,
/Jason
From: Eric Fried <openstack@fried.cc>
Sent: Monday, May 13, 2019 14:54
To: openstack-discuss@lists.openstack.org
Subject: Re: [nova][ironic] Lock-related performance issue with update_resources periodic job
 
Jason-

You may find this article interesting [1]. It isn't clear whether your
issue is the same as CERN's. But it would be interesting to know whether
setting [compute]resource_provider_association_refresh [2] to a very
large number (while leaving your periodic interval at its default) also
mitigates the issue.

Thanks,
efried

[1] https://techblog.web.cern.ch/techblog/post/placement-requests/
[2]
https://docs.openstack.org/nova/latest/configuration/config.html#compute.resource_provider_association_refresh