I've already posted this on the Java GAE group, but maybe someone has
seen this issue on a Python-hosted app.

I'm carrying out some testing of my app against the HR-store, instead
of the M/S datastore, and I've noticed that occasionally I'll get a
request which has a massive CPU spike.  These spikes consume
~30-40seconds of CPU time, when my usual request times are ~500ms.
I'd assumed that something must be fundamentally wrong with my
application against the HR datastore, but I've now had three requests
to AppStats which have the same problem and one of them was an
image!

For example:

/appstats/static/app_engine_logo_sm.gif   200   131ms    31811cpu_ms
<--- Image?!
/appstats/stats   200 536ms         32375cpu_ms
/appstats/stats 200 169ms         23878cpu_ms


Yesterday I had the request below in my log.  It didn't touch the
datastore, had 6 calls to MemCache and according to AppStats had a
grand total time of 125ms.

/user/get 200 156ms     42020cpu_ms

What could cause these large CPU spikes?  They aren't loading
requests, as I'm correctly getting those marked in my logs and they
are in the usual region of 2-3s duration. I also don't experience them
on the same app against the M/S datastore.  My initial thoughts were
that AppStats was potentially the cause of the problem, until I saw
the request for a static image with massive CPU usage!

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