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The Environmental Impact of PHP Compared To C++ On Facebook
Kensai7 writes "Recently, Facebook provided us with some information on their server park. They use about 30,000 servers, and not surprisingly, most of them are running PHP code to generate pages full of social info for their users. As they only say that 'the bulk' is running PHP, let's assume this to be 25,000 of the 30,000. If C++ would have been used instead of PHP, then 22,500 servers could be powered down (assuming a conservative ratio of 10 for the efficiency of C++ versus PHP code), or a reduction of 49,000 tons of CO2 per year. Of course, it is a bit unfair to isolate Facebook here. Their servers are only a tiny fraction of computers deployed world-wide that are interpreting PHP code."
.. because I didn't ever think I'd be defending PHP.
However, it is a much better choice for a web application than C or C++ - and I say that as someone who codes C, C++ and Java for a living. There are no decent web frameworks for C++, memory management is still an issue despite the STL, and the complexity of the language means both staff costs and development time are inflated. Peer review is harder, as the language is fundamentally more difficult to master than PHP. Compared to Java, the development tools are poorer, and things like unit testing a more complicated despite the availability of things like Cppunit. There's no "standard" libraries for things like database access, and no literature that I am aware of that describes how you would go about designing a framework for C++. You'd most likely end up porting something like Spring to C++, and the even if you published your code on the web, I doubt much of a community would build up around it.
If you want a less contentious argument, and one which can be backed up with hard evidence, then argue PHP that should be replaced with Java. A well written Java web application, using a lightweight framework such as Spring or PicoContainer, should outperform ad-hoc C++ code.
The author is pulling numbers out of his ass and has no clue about what uses most time (waiting for database results mostly), about PHP accelerators and about caching systems like memcached.
He's comparing performance of php script running on a raw PHP installation versus running a C++ version of the same script, doing calculations that almost never apply to real world scenarios.
I don't see how any company would use C++ to develop their whole systems except maybe for some CGI scripts. Not even Google does it, afaik they use Perl and Python a lot.
Anyway, the number of servers has no direct correlation to the programming language. Out of those thousands of systems, lots of them are read only database servers in a cluster, lots are only serving static files (thumbnails, images used in CSS files on people's pages and so on), some servers are used solely for memcached instances and content used very rarely, some are load balancers....
Basically, the author has no clue.
I always found Livejournal's presentation about scaling very insightful, especially as it's a pretty big site, just like Facebook and other big time sites. The second link gives a lot of details about how they fine tune mysql and other parts of the system, which just goes to show how the apparent speed improvement of C++ versus PHP can overall be actually insignificant.
http://video.google.com/videoplay?docid=-8953828243232338732&ei=3VUuS5-hLaKi2ALXqanJBQ&q=livejournal#
http://www.danga.com/words/2004_mysqlcon/mysql-slides.pdf
It's more like you decide you want a whole new room dedicated to watching movies, but in order to add that to your current house you'd have to spend tens of thousands of dollars and get approval from city hall and your homeowner's association. Just for a fairly small addition.
So instead you decide to go build a new house the way you like it, from the ground up, and while you're at it you add ethernet outlets into the planning because you always wanted that in your old house but you would have had to take down the drywall in order to get them where you wanted.
Buckle your ROFL belt, we're in for some LOLs.