Mozilla uses a lot of Python. Most of our build system, CI configuration, test harnesses, command line tooling and countless other scripts, tools or Github projects are all handled by Python. In mozilla-central there are over 3500 Python files (excluding third party files), comprising roughly 230k lines of code. Additionally there are 462 repositories labelled with Python in the Mozilla org on Github (though many of these are not active). That’s a lot of Python, and most of it is Python 2.
With Python 2’s exaugural year well underway, it is a good time to take stock of the situation and ask some questions. How far along has Mozilla come in the Python 3 migration? Which large work items lie on the critical path? And do we have a plan to get to a good state in time for Python 2’s EOL on January 1st, 2020?