Google App Engine - What causes cold start latency time to be high, even though my CPU usage is rela

Posted by Spines on Stack Overflow See other posts from Stack Overflow or by Spines
Published on 2010-03-20T04:25:33Z Indexed on 2010/03/20 4:31 UTC
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I've optimized my code to use only lightweight libraries. I'm even using the low level datastore rather than JDO.

And my cold start CPU usage has dropped from about 5 seconds to about 1.5 seconds. However, the time it takes to respond is often about 4.5 seconds, though it varies a lot.

Here are some lines from my logs:

03-19 09:16PM 57.368 /donothing 200 4506ms 1516cpu_ms 0kb Mozilla/5.0
03-19 09:22PM 54.884 /donothing 200 4452ms 1477cpu_ms 0kb Mozilla/5.0

What is the app engine doing for those extra 3 seconds that apparently isn't using any CPU?

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