Open Stack

On Wed, Jan 27, 2016 at 05:06:03PM EST, Assaf Muller wrote:
> >> RDO systemd init script for the L3 agent will send a signal 15 when
> >> 'systemctl restart neutron-l3-agent' is executed. I assume
> >> Debian/Ubuntu do the same. It is imperative that agent restarts do not
> >> cause data plane interruption. This has been the case for the L3 agent
> >
> > But wouldn't it really be wiser to use SIGHUP to communicate the intent
> > to restart a process?
> 
> Maybe. I just checked and on a Liberty based RDO installation, sending
> SIGHUP to a L3 agent doesn't actually do anything. Specifically it
> doesn't resync its routers (Which restarting it with signal 15 does).

See, but there must be something that is starting the neutron l3 agent
again, *after* sending it a SIGTERM (signal 15). Then the l3 agent does
a full resync since it's started back up, based on some state accounting
done in what appears to be the plugin. Nothing about signal 15 actually
does any restarting. It just terminates the process.

> 2016-01-27 20:45:35.075 14651 INFO neutron.agent.l3.agent [-] Agent has just been revived. Doing a full sync.

https://github.com/openstack/neutron/blob/ea8cafdfc0789bd01cf6b26adc6e5b7ee6b141d6/neutron/agent/l3/agent.py#L697

https://github.com/openstack/neutron/blob/ea8cafdfc0789bd01cf6b26adc6e5b7ee6b141d6/neutron/agent/l3/agent.py#L679


-- 
Sean M. Collins