PHP 7 at Tumblr

At Tumblr, we’re always looking for new ways to improve the performance of the site. This means things like adding caching to heavily used codepaths, testing out new CDN configurations, or upgrading underlying software.

Recently, in a cross-team effort, we upgraded our full web server fleet from PHP 5 to PHP 7. The whole upgrade was a fun project with some very cool results, so we wanted to share it with you.


It all started as a hackday project in the fall of 2015. @oli and @trav got Tumblr running on one of the PHP 7 release candidates. At this point in time, quite a few PHP extensions did not have support for version 7 yet, but there were unofficial forks floating around with (very) experimental support. Nevertheless, it actually ran!

This spring, things were starting to get more stable and we decided it was time to start looking in to upgrading more closely. One of the first things we did was package the new version up so that installation would be easy and consistent. In parallel, we ported our in-house PHP extensions to the new version so everything would be ready and available from the get-go.

A small script was written that would upgrade (or downgrade) a developer’s server. Then, during the late spring and the summer, tests were run (more on this below), PHP package builds iterated on and performance measured and evaluated. As things stabilized we started roping in more developers to do their day-to-day work on PHP 7-enabled machines.

Finally, in the end of August we felt confident in our testing and rolled PHP 7 out to a small percentage of our production servers. Two weeks later, after incrementally ramping up, every server responding to user requests was updated!


Originally published at