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Bug 2134365

Summary:	[OVN] Hash Ring nodes considered dead because of delayed probing
Product:	Red Hat OpenStack	Reporter:	Lucas Alvares Gomes <lmartins>
Component:	python-networking-ovn	Assignee:	Lucas Alvares Gomes <lmartins>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Vadim Khitrin <vkhitrin>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	16.2 (Train)	CC:	apevec, ekuris, jlibosva, jschluet, lhh, majopela, scohen, vkhitrin
Target Milestone:	z5	Keywords:	TestOnly, Triaged
Target Release:	16.2 (Train on RHEL 8.4)
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	python-networking-ovn-7.4.2-2.20220409154864.el8ost	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:	2134364	Environment:
Last Closed:	2023-10-06 10:32:22 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2134364
Bug Blocks:

Description Lucas Alvares Gomes 2022-10-13 09:20:20 UTC

+++ This bug was initially created as a clone of Bug #2134364 +++

Right now, probing the hash ring nodes happens as part of the maintenance task thread but this thread is only started after we establish a connection with the OVSDB servers in the post_fork_initialize() method for ML2/OVN.

If this connection with OVSDB takes longer than expected, it's possible that the nodes in the hash ring (that have to be added prior to this connection) will time out because the maintenance task thread has not yet being started.

Ideally, we would need to separate the probing to it's own periodic thread that is started before the connections with the OVSDBs to avoid this problem.

This BZ is related to the initial work done at: https://bugzilla.redhat.com/show_bug.cgi?id=2125828

Comment 2 Lon Hohberger 2023-04-21 10:39:30 UTC

According to our records, this should be resolved by python-networking-ovn-7.4.2-2.20220409154865.el8ost.  This build is available now.

Comment 3 Vadim Khitrin 2023-10-05 10:55:04 UTC

Verified on compose `RHOS-16.2-RHEL-8-20230926.n.1`:
```
[root@controller-0 containers]# grep -iR 'Hash Ring probing thread has started' /var/log/containers/
/var/log/containers/neutron/server.log.1:2023-10-04 08:09:16.400 16 INFO networking_ovn.ml2.mech_driver [-] Hash Ring probing thread has started
/var/log/containers/neutron/server.log.1:2023-10-04 10:23:43.229 16 INFO networking_ovn.ml2.mech_driver [-] Hash Ring probing thread has started
[root@controller-0 containers]# grep -iR 'Maintenance task thread has started' /var/log/containers/
/var/log/containers/neutron/server.log.1:2023-10-04 08:09:16.972 22 INFO networking_ovn.ml2.mech_driver [-] Maintenance task thread has started
/var/log/containers/neutron/server.log.1:2023-10-04 10:23:43.748 21 INFO networking_ovn.ml2.mech_driver [-] Maintenance task thread has started
```