Hi all,
it's been quite a journey since we started working on HHVM, and last
week (November 25th) HHVM was finally introduced to all users who didn't
opt-in to the beta feature.
Starting on monday, we started reinstalling all the 150 remaining
servers that were running Zend's mod_php, upgrading them from Ubuntu
precise to Ubuntu trusty in the process. It seemed like an enormous task
that would require me weeks to complete, even with the improved
automation we built lately.
Thanks to the incredible work by Yuvi and Alex, who helped me basically
around the clock, today around 16:00 UTC we removed the last of the
mod_php servers from our application server pool: all the non-API
traffic is now being served by HHVM.
This new PHP runtime has already halved our backend latency and page
save times, and it has also reduced significantly the load on our
cluster (as I write this email, the average cpu load on the application
servers is around 16%, while it was easily above 50% in the pre-HHVM era).
The API traffic is still being partially served by mod_php, but that
will not be for long!
Cheers,
Giuseppe
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Giuseppe Lavagetto
Wikimedia Foundation - TechOps Team