Mozmill speed improvements after upgrading Python from 2.6 to 2.7.3

Yesterday we tried to upgrade our mozmill-ci cluster to the previously released Mozmill 2.0.1. Sadly we failed on the OS X 10.6 machines and had to revert this change. After some investigation I found out that incompatibility issues between Python 2.6 and 2.7.3 were causing this problem in mozprofile. Given the unclear status of Python 2.6 support in mozbase, and a talk in the #ateam IRC channel, I have been advised to upgrade those machines to Python 2.7. I did so after some testing, also because all other machines are running Python 2.7.3 already. So I didn’t expect any fallout. First post upgrade tests have proven this.

The interesting fact I would like to highlight here is that we can see speed improvements by running our tests now. Previously a functional testrun on 10.6 has been taken about 15 minutes. Now after the upgrade it went down to 11 minutes only. That’s an improvement of nearly 27% with Mozmill 1.5.24. With Mozmill 2.0.1 there is a similar drop which is from 8 minutes to 6 minutes.

Given all that and the upcoming upgrade (hopefully soon) of our mozmill-ci system to Mozmill 2.0.1 we will see an overall improvement of 60% (15 minutes -> 6 minutes) per testrun!! This is totally stunning and allows us to run 2.5 times more tests in the same timespan. With it we can further increase our coverage for locales from 20 to 40 for beta and release candidate builds as next step.