Thank you for that interesting post. Some points though:
- behavior is observed at the same time each day
- behavior is observed when QPS is lowest
- behavior is not observed at high QPS
Object datamodel:
class Score(db.Model):
a = db.StringProperty(indexed=False)
b = db.ReferenceProperty(indexed=False)
c = db.StringProperty(indexed=False)
d = db.StringProperty(indexed=False)
e = db.StringProperty(indexed=False)
f = db.IntegerProperty(indexed=False)
g = db.StringProperty(indexed=False)
h = db.IntegerProperty(indexed=False)
i = db.IntegerProperty(indexed=False)
j = db.TextProperty(indexed=False)
I really don't think this is the problem. Unless it is happening to
another app on the same hardware, and I am seeing issues too ? Not sure if
that is possible ?
On Tuesday, July 31, 2012 12:30:17 AM UTC-4, Takashi Matsuo (Google) wrote:
>
> 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
>
> >
> >
> > --
> > You received this message because you are subscribed to the Google
> Groups
> > "Google App Engine" group.
> > To view this discussion on the web visit
> > https://groups.google.com/d/msg/google-appengine/-/tGsoCfpFC_kJ.
> >
> > To post to this group, send email to [email protected].
> > To unsubscribe from this group, send email to
> > [email protected].
> > For more options, visit this group at
> > http://groups.google.com/group/google-appengine?hl=en.
>
>
>
> --
> Takashi Matsuo
>
--
You received this message because you are subscribed to the Google Groups
"Google App Engine" group.
To view this discussion on the web visit
https://groups.google.com/d/msg/google-appengine/-/Sgdd6z4nzPsJ.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/google-appengine?hl=en.
