Open Stack

On Fri, Mar 21, 2014 at 8:58 AM, Doug Hellmann
<doug.hellmann at dreamhost.com>wrote:

>
>
>
> On Fri, Mar 21, 2014 at 7:04 AM, Sean Dague <sean at dague.net> wrote:
>
>> On 03/20/2014 06:18 PM, Joe Gordon wrote:
>> >
>> >
>> >
>> > On Thu, Mar 20, 2014 at 3:03 PM, Alexei Kornienko
>> > <alexei.kornienko at gmail.com <mailto:alexei.kornienko at gmail.com>> wrote:
>> >
>> >     Hello,
>> >
>> >     We've done some profiling and results are quite interesting:
>> >     during 1,5 hour ceilometer inserted 59755 events (59755 calls to
>> >     record_metering_data)
>> >     this calls resulted in total 2591573 SQL queries.
>> >
>> >     And the most interesting part is that 291569 queries were ROLLBACK
>> >     queries.
>> >     We do around 5 rollbacks to record a single event!
>> >
>> >     I guess it means that MySQL backend is currently totally unusable in
>> >     production environment.
>> >
>> >
>> > It should be noticed that SQLAlchemy is horrible for performance, in
>> > nova we usually see sqlalchemy overheads of well over 10x (time
>> > nova.db.api call vs the time MySQL measures when slow log is recording
>> > everything).
>>
>> That's not really a fair assessment. Python object inflation takes time.
>> I do get that there is SQLA overhead here, but even if you trimmed it
>> out you would not get the the mysql query time.
>>
>> That being said, having Ceilometer's write path be highly tuned and not
>> use SQLA (and written for every back end natively) is probably
>> appropriate.
>>
>
> I have been working to get Mike Bayer (author of SQLAlchemy) to the summit
> in Atlanta. He is interested in working with us to improve SQLAlchemy, so
> if we have specific performance or feature issues like this, it would be
> good to make a list. If we have enough, maybe we can set aside a session in
> the Oslo track, otherwise we can at least have some hallway conversations.
>


That would be really amazing. Is he on IRC, so we can get the ball rolling?


>
> Doug
>
>
>
>>
>>         -Sean
>>
>> --
>> Sean Dague
>> Samsung Research America
>> sean at dague.net / sean.dague at samsung.com
>> http://dague.net
>>
>>
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>
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