use Perl

The depressing thing about discussions like this is how much misinformation gets spread around. Here are a few examples:

• The guy on Slashdot claiming that Apache 1 scales badly (that must be why nearly all of the largest websites in the world use it) and that a piddly little site like aceshardware.com proves the necessity of Apache 2 and a threaded model.
• The guy who misread the abstract of an ACM article and is now posting all over the place that Java outperformed Perl and PHP by 8 times on a benchmark in this article. (Totally wrong. The article says that static pages were 8 times as fast as dynamic pages, and that Java sometimes outperformed the others and sometimes was slower.)
• The PHP proponent who thinks that George Schlossnagle's article about PHP and Oracle where he says to use the equivalent of the mod_perl reverse proxy setup shows some kind of application-specific thinking on the part of PHP developers. (It's just a standard workaround that anyone who uses PHP or mod_perl would use to keep from wasting database connections in apache processes that are serving images. Java servlet architectures do not normally have this problem, and thus don't need this workaround.)
• The people claiming that Yahoo does everything in PHP. PHP just replaced some in-house proprietary templating systems at Yahoo. Yahoo still uses C/C++ and Perl for the bulk of their applications, with PHP just serving as the final delivery engine, like a fancy SSI.
• Even Rasmus Lerdorf with his mantra about how PHP is a "shared nothing" architecture sounds a bit disingenuous. Any interesting dynamic application is going to share something, probably through a database, with possibly some additional sharing in files or shared memory or a database-like daemon such as memcached. The mechanisms for sharing this data on a cluster of PHP servers are essentially the same as the ones for doing it with Java servers.

There is one thing about Java which can be a problem for scalability, and that is the proprietary nature of many of the server environments people run it on. If you buy a commercial J2EE server, the vendor will promise you incredibly scalable session data storage and database caching, but they will typically not tell you how they do it. When you run into trouble, you have no knobs to twiddle and no alternate options because the whole thing is closed to you. This is why I would recommend that people wanting to use a Java solution should look at the open source tools instead, especially the new lightweight ones.

The most unfortunate thing about this PHP/Java discussion is that people still aren't talking about the things that actually do make a system scalable, like ways of limiting the resources that each active user on the site takes up, and ways of handling overload gracefully.

Okay, I guess I had a little more to say about this than I thought. I'm going to stop here for now. Maybe some of this will filter into my OSCON talk.