[DEFAULT] rpc_worker=0 leaves one rpc worker

[Takashi Kajinami]

Since https://review.opendev.org/c/openstack/neutron/+/823637 was merged, neutron-server allows disabling rpc worker by setting::

[DEFAULT]
rpc_worker=0

However, I observe one rpc worker is still kept even with this setting.

From neutron-server log, rpc_workers and rpc_state_report_workers are set to 0.

2024-02-05 13:05:33.159 70458 DEBUG neutron.common.config [-] rpc_state_report_workers = 0 log_opt_values /usr/lib/python3.9/site-packages/oslo_config/cfg.py:2602
2024-02-05 13:05:33.159 70458 DEBUG neutron.common.config [-] rpc_workers = 0 log_opt_values /usr/lib/python3.9/site-packages/oslo_config/cfg.py:2602

ps shows there is one rpc worker running.

neutron 70458 1 70458 0.3 1.8 133664 144496 /usr/bin/python3 -s /usr/bin/neutron-server ...
neutron 70499 70458 70499 11.4 3.1 246792 248240 neutron-server: api worker (...)
neutron 70500 70458 70500 11.0 3.1 243640 249488 neutron-server: api worker (...)
neutron 70502 70458 70502 0.3 1.7 141196 142132 neutron-server: rpc worker (...)
neutron 70503 70458 70503 0.3 1.8 145256 146356 neutron-server: MaintenanceWorker (...)
neutron 70504 70458 70504 0.0 1.7 135472 135604 neutron-server: periodic worker (...)

I've noticed this in Puppet OpenStack jobs which uses RDO master packages.

The package versions currently used are::

openstack-neutron-24.0.0-0.20240131211457.b85b19e.el9.noarch
openstack-neutron-common-24.0.0-0.20240131211457.b85b19e.el9.noarch
openstack-neutron-ml2-24.0.0-0.20240131211457.b85b19e.el9.noarch
openstack-neutron-ovn-agent-24.0.0-0.20240131211457.b85b19e.el9.noarch
openstack-neutron-ovn-metadata-agent-24.0.0-0.20240131211457.b85b19e.el9.noarch
openstack-neutron-rpc-server-24.0.0-0.20240131211457.b85b19e.el9.noarch

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/908173

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/908173
Committed: https://opendev.org/openstack/neutron/commit/b38f72b2129ee377cb80132ca9c0794b60585be6
Submitter: "Zuul (22348)"
Branch: master

commit b38f72b2129ee377cb80132ca9c0794b60585be6
Author: Takashi Kajinami <email address hidden>
Date: Wed Feb 7 01:46:47 2024 +0900

    Completely disable rpc workers when rpc_workers=0

    Currently at least 1 rpc worker is launched even when a user requests
    zero workers by setting rpc_workers=0. The setting of rpc_workers=0 is
    used when ml2-ovn plugin is used without any additional agent, and in
    this deployment pattern the single rpc worker is not at all used.

    This change ensures no rpc worker is launched when rpc_workers options
    is explicitly set to 0. This may be classified as a breaking change,
    but is consistent with the earlier change[1] for rpc_workers=0.

    [1] 3e1e2d63b3383d28c9a36b00000ab89caffa3829

    Closes-Bug: #2052484
    Change-Id: I878e50c3192ecd3b145ded0ab8394845a089696e

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 24.0.0.0rc1 release candidate.