bbillings's comments

Is a pretty good explanation of why we don't rewrite the whole site. A rewrite would involve every product dev stopping what they are doing and probably spending at least 18 months reimplementing their product in a different language. During that time all forward progress on products would be halted. I am absolutely certain it would be an unmitigated disaster for the company to try to rewrite the site in another language.

Instead we have a small team of people making PHP really nice work work in. HipHop gives us full control over the language and lets us add in any constructs we like. We make sure stock PHP runs, but also the additions we need to the language can be added as well.

I don't really understand devs who think reimplementing in another language is easy or the right thing to do. It's almost always the wrong thing from my experience and always lot harder and takes a lot longer than expected.

I personally disagree pretty heavily on sleeping in the office and working crazy hours. I find it very counter productive and generally think it leads to bad decisions, bad code, and ultimately bad products. It is certainly the exception, and not something you should be doing if you aren't 22 years old and/or more than a little crazy. I personally haven't worked crazy hours at Facebook since probably 2009.

Talking about this sort of thing from a PR perspective seems has to balance getting people excited about our environment and explaining our goals and day-to-day. I've found it's something the media outlets love to play up. The normal day-in-the-life of an engineer is fun, but chill, and not particularly news worthy.

Too my knowledge (I'm not directly on the Hip-Hop team) it will be open sourced, additionally we also generally present a PHP patch as well to allow it in future versions of standard PHP.

I've managed inside Engineering at Facebook and am now back to just being a straight Engineer, and my advice to everyone I work with is the same: Don't kill yourself working 70/80 hour weeks. We pay you to give 40 solid hours, and that is what I want. What I ask of you is that you set expectations for the people and teams around you as accurately as you can. Don't make a bunch of promises you have to work crazy hours to keep.

The majority of our most successful engineers have a very good work-life balance.

Syntactically it looks a lot like PHP and is backward compatible for many thing, but it's not really PHP anymore. The HipHop team has done a ton to make the language a lot more enjoyable to work in.

http://phabricator.org/ has a very similar system if you are curious. epriestley made some nice updates to it in there as well.

File A includes File B includes File C includes File A by about 10000 files.

It was for a very scary trying to change a core library during this time because it was almost impossible to figure out where all it was included and impossible to test all the code that touched it. Additionally, we were basically loading up our entire init stack on every page load and async request because as soon as you loaded up one file all the circular dependencies would load up the entire stack. This had a big performance overhead prior to our switch to HipHop.

To this end we developed a new include system for library files that forces developers to be sane. Every module in the our library files must explicitly include everything that they need and it forbids circular dependencies. If module A requires module B, module B cannot require module A.

Making this change took a long time (in some places we are still untangling the code), but our core code is now infinitely more manageable and most importantly testable.

We also maintain a robust employee list that is cached in APC on every web host that you can always call an is_employee style function for any user ID on. The careers site in particular has some employee only functionality that this endpoint is probably checking.