Open Stack

On 5/19/2014 1:25 PM, Sean Dague wrote:
> On 05/19/2014 02:13 PM, Matt Riedemann wrote:
>>
>>
>> On 5/19/2014 11:33 AM, Matt Riedemann wrote:
>>>
>>>
>>> On 5/19/2014 10:53 AM, Matt Riedemann wrote:
>>>> I was looking through this timeout bug [1] this morning and am able to
>>>> correlate that around the time of the image snapshot timeout, ceilometer
>>>> was really hammering CPU on the host.  There are already threads on
>>>> ceilometer performance and how that needs to be improved for Tempest
>>>> runs so I don't want to get into that here.
>>>>
>>>> What I'm thinking about is if there is a way to be smarter about how we
>>>> do timeouts in the tests, rather than just rely on globally configured
>>>> hard-coded timeouts which are bound to fail intermittently in dynamic
>>>> environments like this.
>>>>
>>>> I'm thinking something along the lines of keeping track of CPU stats on
>>>> intervals in our waiter loops, then when we reach our configured
>>>> timeout, calculate the average CPU load/idle and if it falls below some
>>>> threshold, we cut the timeout in half and redo the timeout loop - and we
>>>> continue that until our timeout reaches some level that no longer makes
>>>> sense, like once it drops less than a minute for example.
>>>>
>>>> Are there other ideas here?  My main concern is the number of random
>>>> timeout failures we see in the tests and then people are trying to
>>>> fingerprint them with elastic-recheck but the queries are so generic
>>>> they are not really useful.  We now put the test class and test case in
>>>> the compute test timeout messages, but it's also not very useful to
>>>> fingerprint every individual permutation of test class/case that we can
>>>> hit a timeout in.
>>>>
>>>> [1] https://bugs.launchpad.net/nova/+bug/1320617
>>>>
>>>
>>> This change to devstack should help [1].
>>>
>>> It would be good if we actually used the default timeouts we have
>>> configured in Tempest rather than hard-coding them in devstack based on
>>> the latest state of the gate at the time.
>>>
>>> [1] https://review.openstack.org/#/c/94221/
>>>
>>
>> I have a proof of concept up for Tempest with adjusted timeouts based on
>> CPU idle values here:
>>
>> https://review.openstack.org/#/c/94245/
>
> The problem is this makes an assumption that Tempest is on the host
> where the services are. We actually need to get away from that assumption.
>
> If there is something in ceilometer that would make sense to poll, that
> might be an option. But psutils definitely can't be a thing we us here.
>
> 	-Sean
>
>
>
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>

I've abandoned both changes in great shame. :P

To target the timeout failure in the image snapshot tests and bug 
1320617, I'm looking to see if maybe the experimental tasks API in 
glance v2 could help get some diagnostic information at the point of 
failure to see if things are just slow or if the snapshot is actually 
hung and will never complete.

Ideally we could leverage tasks across the services for debugging issues 
like this.

-- 

Thanks,

Matt Riedemann