Open Stack

hi,

this seems to be similar to a bug we were tracking in earlier[1]. 
basically, any service with a listener never seemed to idle properly.

based on earlier investigation, we found it relates to the heartbeat 
functionality in oslo.messaging. i'm not entirely sure if it's because 
of it or some combination of things including it. the short answer, is 
to disable heartbeat by setting heartbeat_timeout_threshold = 0 and see 
if it fixes your cpu usage. you can track the comments in bug.

[1] https://bugs.launchpad.net/oslo.messaging/+bug/1478135

On 17/02/2016 4:14 AM, Gyorgy Szombathelyi wrote:
> Hi!
>
> Excuse me, if the following question/problem is a basic one, already known problem,
> or even a bad setup on my side.
>
> I just noticed that the most CPU consuming process in an idle
> OpenStack cluster is ceilometer-collector. When there are only
> 10-15 samples/minute, it just constantly eats about 15-20% CPU.
>
> I started to debug, and noticed that it epoll()s constantly with a zero
> timeout, so it seems it just polls for events in a tight loop.
> I found out that the _maybe_ the python side of the problem is
> oslo_messaging.get_notification_listener() with the eventlet executor.
> A quick search showed that this function is only used in aodh_listener and
> ceilometer_collector, and both are using relatively high CPU even if they're
> just 'listening'.
>
> My skills for further debugging is limited, but I'm just curious why this listener
> uses so much CPU, while other executors, which are using eventlet, are not that
> bad. Excuse me, if it was a basic question, already known problem, or even a bad
> setup on my side.
>
> Br,
> György
>
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-- 
gord