Now Facebook, which also runs on PHP, has announced a new version of PHP that runs twice as fast.

This also means that if you have a popular WordPress blog, you might only have to have half the server size you use now.

How PHP Works

PHP, in its usual incarnation, is an interpreted language. This means that a program (such as a PHP module in the Apache webserver) reads the PHP instructions in your script and executes them in turn. Every time the PHP script is executed, it has to be turned into machine code, even if the script runs 1000 times per hour. Obviously, this is inefficient, but people put up with it because PHP is considered easier to develop in than other languages.

By comparison, C++ is a language which is usually compiled (changed to machine instructions which run directly on the CPU). This happens only once, and every time the program runs, it runs directly on the processor. Because there’s no intermediate interpretation step, C++ programs run much faster.

Facebook’s HipHop PHP

Facebook announced what they are calling HipHop PHP, which translates PHP into C++. Then you use g++, the GNU C++ compiler, to compile the C++ program.

Here’s how the process works:

HipHop PHP Transformation Process

Facebook says compilation of their PHP code results in savings of 50% in server usage.

They also released HPHPi, which is an optimized PHP interpreter that doesn’t require you re-compile your code.

Download HipHop PHP

Facebook is going to release the code to HPHP under the PHP license on Github for download at this address (but it’s not there yet).

Caveats

In order to optimize PHP to the maximum, they left out some rarely used dynamic functionality, such as the eval() function.

I’ll report more on HipHop PHP as Facebook releases more information.

Resources

Facebook HipHop PHP announcement

HipHop release video

Facebook HipHop developer mailing list

ZDNet article

HipHop for PHP: Who Benefits?

BestTechie article

Feed2Meme article

Facebook’s HipHop Goes Public With a New PHP Runtime

PHPC: A PHP Compiler

Roadsend PHP compiler

An interview with a Facebook employee about PHP

PHP Facebook release

Top Incoming Search Terms

Related posts:

1. How Facebook Runs PHP and MySQL
2. The Origins of Facebook, Hacked E-mails, and Privacy
3. Back Up Gmail, Facebook, WordPress, and Other Social Media with Backupify

It also uses C++ and Java in places, but it’s the fact that it uses the little scripting language that could (PHP) is what is interesting. Aditya Agarwal of Facebook describes how the social networking giant does it in a presentation at QCon SF 2008.

The story is being discussed on Slashdot here.

Top Incoming Search Terms

Related posts:

1. Facebook Announces a Better, Faster PHP: HipHop PHP
2. The Origins of Facebook, Hacked E-mails, and Privacy
3. Facebook Surpasses Google: What Does It Mean?