The Wikimedia Foundation has been employing HHVM to run MediaWiki in production since 2014. Since then, a few things happened that made it compelling for us to move back to the "official" PHP interpreter:
- PHP 7.x has brought huge performance improvements, so that its performance is nowadays comparable to, if not better than, HHVM for our needs.
- HHVM has dropped support for pure PHP in favour of Hack, an "evolution" of PHP which doesn't have widespread support.
You can verify that it is enabled for you by visiting Special:Version on your wiki, and checking that it says "php" instead of "HHVM" in the "Installed software" table.
Questions and answers
I am a non-technical user. What does this mean?
Hopefully nothing. This is about changing the software used to run the wiki's code. Ideally, you should notice no real difference.
When will this happen?
Work began in 2017 and ramped up over 2018. The beta feature is available since January 2019, and PHP 7 support should be production-complete in the first half of 2019.
What should I do if I find an issue?
Report it on Phabricator, in the PHP 7.2 support project.
Why are edits being tagged?
This will help us identify performance, functional and stability concerns specific to PHP in comparison to HHVM. You can ignore the PHP7 tags.