[openstack-dev] [Neutron] L3 agent rescheduling issue

Salvatore Orlando sorlando at nicira.com
Thu Jun 4 14:54:32 UTC 2015


One reason for not sending the heartbeat from a separate greenthread could
be that the agent is already doing it [1].
The current proposed patch addresses the issue blindly - that is to say
before declaring an agent dead let's wait for some more time because it
could be stuck doing stuff. In that case I would probably make the
multiplier (currently 2x) configurable.

The reason for which state report does not occur is probably that both it
and the resync procedure are periodic tasks. If I got it right they're both
executed as eventlet greenthreads but one at a time. Perhaps then adding an
initial delay to the full sync task might ensure the first thing an agent
does when it comes up is sending a heartbeat to the server?

On the other hand, while doing the initial full resync, is the  agent able
to process updates? If not perhaps it makes sense to have it down until it
finishes synchronisation.

Salvatore

[1]
http://git.openstack.org/cgit/openstack/neutron/tree/neutron/agent/l3/agent.py#n587

On 4 June 2015 at 16:16, Kevin Benton <blak111 at gmail.com> wrote:

> Why don't we put the agent heartbeat into a separate greenthread on the
> agent so it continues to send updates even when it's busy processing
> changes?
> On Jun 4, 2015 2:56 AM, "Anna Kamyshnikova" <akamyshnikova at mirantis.com>
> wrote:
>
>> Hi, neutrons!
>>
>> Some time ago I discovered a bug for l3 agent rescheduling [1]. When
>> there are a lot of resources and agent_down_time is not big enough
>> neutron-server starts marking l3 agents as dead. The same issue has been
>> discovered and fixed for DHCP-agents. I proposed a change similar to those
>> that were done for DHCP-agents. [2]
>>
>> There is no unified opinion on this bug and proposed change, so I want to
>> ask developers whether it worth to continue work on this patch or not.
>>
>> [1] - https://bugs.launchpad.net/neutron/+bug/1440761
>> [2] - https://review.openstack.org/171592
>>
>> --
>> Regards,
>> Ann Kamyshnikova
>> Mirantis, Inc
>>
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