Beta Features/PHP7

PHP7 is a system to run PHP. The Wikimedia Foundation is moving all Wikimedia wikis to use PHP7 in early 2019. It replaces HHVM, to which Wikimedia moved in 2014. PHP7 will be available from January 2019.

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.

It should have roughly the same performance behaviour as before.

Questions

 * Why are you switching to PHP7?
 * The HHVM team announced in September 2017 that they were moving away from PHP support in favour of Hack, their own variant of the language. After some discussion and an RfC, the Wikimedia technical community agreed to move away from HHVM support and back to PHP.
 * When will this happen?
 * Work began in 2017, ramped up over 2018, and should be production-complete in 2019.
 * What should I do if I find an issue?
 * Report it.
 * Why are edits being tagged?
 * This will help us identify performance and stability concerns specific to PHP in comparison to HHVM. You can ignore them.