Why Facebook's HipHop for PHP is important

Facebook formally announced a long-rumored project it has been working on called HipHop for PHP.

According to the announcement, HipHop is a code transformer that turns PHP code into "highly optimized C++." By using HipHop on their servers, Facebook has been able to reduce CPU usage by over 50%, and substantially increase the speed of their pages. All without giving up the "rapid pace of development that PHP offers." As the announcement notes:

"Overall HipHop allows us to keep the best aspects of PHP while taking advantage of the performance benefits of C++. In total, we have written over 300,000 lines of code and more than 5,000 unit tests. All of this will be released this evening on GitHub under the open source PHP license."

Speeding up PHP is important, because (as Terry Chay has often said) for most of the web era the major constraint on application speed has been database performance. So, the fact that PHP is relatively slow, wasn’t an issue in the past. Now, with data caching solutions like MemCached, the performance of PHP has become more important, particularly for large-scale sites like Facebook.

Facebook is holding a developer event tonight at which they will release more details on HipHop. You can see it streamed at http://developers.facebook.com/news.php?blog=1&story=358 at 7:30 PM Pacific.