Set python version takes a weirdly long time


Two different project, two different Python versions: in both cases, it can take 2-3min of test time set up the Python version. I’ve found this to be a major flow-killer, especially in the case of a project whose tests take ~15 seconds to run.


…looks like Python is downloaded directly from every time, which surprises me.



What versions of python are you trying to set? Also, what version of Ubuntu is set in your build environment? Note that python 3.5.1, for example, is only available in the Ubuntu 14.04 image (, and thus setting it in Ubuntu 12.04 ( will cause it to download and install from


Here are two recent examples showing a lengthy Python version setup:

Your explanation helps with the second one, but what about the first?


bumping this question


Also experiencing weirdly long times for setting Python to 2.7 (or 2.7.6 or 2.7.12). Does anyone have a solution?


think the solution is to not specify python from circle.yml (since its not part of the built image…)

then, youd want to do a custom pyenv install (or perhaps some other method… doesnt matter for this discussion) then caching the install during the depency cache stage…

the python install command should also first check that the custom / cached version doesnt already exist (just to cover my ass in stating…)

that should add a couple more tedium steps to tinker and fuck around with the process from first run, cached subsequent runs, etc. but not that crazy. not my ex-gf.