Hi Richard,

I'm still not 100% sure, but my first guess is that it might be
because of datastore tablets splitting/merging behavior. When you
create or delete lots of entities, the datastore tablets might be
splited/merged into larger/fewer number of tablets. If that happens,
you may experience such high latencies.

This blog post by Ikai explains this issue very well:
http://ikaisays.com/2011/01/25/app-engine-datastore-tip-monotonically-increasing-values-are-bad/

Questions are:
How often those entities are created? How much QPS?
What kind of keys do you use for those small entities?

If you write entities at a somewhat high rate like >100QPS, and you're
using keys which are not distributed well, the culprit might be
splitting/merging behavior mentioned above.

Also, maybe you can consider using pull queues for such tasks.

-- Takashi


On Tue, Jul 31, 2012 at 4:04 AM, Richard <[email protected]> wrote:
> And, of course.... including an image from Google docs does not actually
> work.   Grrr!
>
> https://docs.google.com/drawings/pub?id=1nbrpRb7bSYIvS7329fY2jmynKCJOtUtlCMImo0wXnpE&w=1440&h=1080
>
>
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-- 
Takashi Matsuo

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