3.30 (due mid-December) will be the last HHVM release that aims to support PHP: https://hhvm.com/blog/2018/09/12/end-of-php-support-future-of-hack.html

If it's practical, I'm going to do it even if it's not necessary for Wikipedia - breaking things 4 days before the end of support and not fixing them isn't ideal, and we have other reports of this issue.

Also:

• From Facebook's perspective, HHVM 3.18 is unsupported as of 2018-01-16; that said, I'm likely to make an exception for the a fix for this issue given how recently we introduced the regression, if backporting it isn't too involved.
• Travis uses our packages, not the DFSG ones
• We're not ready to announce this yet (want a little more testing first), but as of last week, we started packaging for Trusty again, and Travis now has 3.21 and 3.24 available: https://travis-ci.org/fredemmott/travistest/builds/333382730

https://gist.github.com/fredemmott/39c9abef4571f1e337d339fd8355da60 should resolve this, and will hopefully land to HHVM master, 3.21, and 3.24 in the next few days.

I'm not directly working on HHVM any more, though I'll see if I can get that issue prioritized: the trigger here is https://github.com/facebook/hhvm/commit/d7ce713deeb541e05c0b2b66c30114f6931c1bb5

Is there any data yet from wikipedia deployments?

TinyRGB can be redistributed under the terms of CC0, available at https://creativecommons.org/publicdomain/zero/1.0/

We're likely to make this available under CC0 - hopefully will have this finalized soon :)

Re-ran the benchmarks.

More results:

• if you were already using repo-auth, this would be a 12% improvement
• if you were using PHP7, this would be a ~ 1% improvement

Done

Looked at this in a bit more detail - as well as array access being faster, the main advantage is actually that this significantly reduces the use of unserialize(), which does a lot of memcpys when making the strings.

This naive implementation shows a ~ 7% win on HHVM, without using repo-authoritative mode: https://gist.github.com/fredemmott/2f760a7702ac2234d38a