Open Stack

The review to land the first entrypoints switch over in nova passed 
through review and hit jenkins this afternoon - 
https://review.openstack.org/#/c/11027/ and Jenkins failed it on a 
timeout (exceeded 30 minutes to run).

Clark helpfully suggested that the patch might actually have had a 
performance impact, so I've been collecting data, and it did.

On a decent blade with a spinning disk.

Before the change the nova unit tests are running: ~385s (385.158s
, 386.089s on two runs to ensure no cache effects).

After that change the nova unit tests are running: ~920s (919.561s, 
922.514s)


2.3 times slower.


On my laptop (SSD) the effect is there, but not quite as dramatic: ~450s 
vs ~600s.

So only 30% slower.


While I get that in production, the class loading will disappear in the 
noise, that huge hit on the unit tests seems really problematic from a 
developer point of view. And a big problem from a CI perspective. Anyone 
have ideas on why this is such a huge hit, or thoughts on how to 
mitigate it?

	-Sean

-- 
Sean Dague
IBM Linux Technology Center
email: sdague at linux.vnet.ibm.com
alt-email: sldague at us.ibm.com