What steps will reproduce the problem?
1. Build a 0.96 Django project, apply AppEngine patch, upload to GAE -
beyond that I don’t know.


What is the expected output? What do you see instead?

The problem is unexpected high CPU usage
08-08 11:12AM 11.077 / 200 2501ms 3008cpu_ms 124api_cpu_ms 0kb
…
zipimporter(’/base/data/home/apps/MY_APP_NAME/5.335434339950952156/common/zip-packages/django-1.0.2.zip’,
’’)


What version of the product are you using? On what operating system?
Django 0.96, Python 2.5, GAE

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Google keeps the imports cached for a certain amount of time (maybe a few seconds).

If you are getting hits at a lower frequency, like once every minute, the zipimport
has to happen again, and you’ll get the CPU hit. This looks very scary, because the
CPU usage on your site will start creeping towards the free CPU quota.

The good news is, when traffic goes up, this problem goes away, so don’t worry too
much about it. When your site is getting a few hits a second or more, the imports
stay cached pretty much all the time, and CPU usage actually goes way down.

To prove this is happening, you can put this at the top of views.py:

import logging

logging.info("re-imported views.py (and re-imported django.zip)")

That log message will happen only when views.py is re-imported (due to it not being
cached anymore). You’ll notice that the above log message will happen in lock-step
with the big CPU warnings.