Then look up what yahoo did for apache tuning. They hacked a flavor of apache called yapache, I think, which handles high load well. They explain a lot of the simple things they did and why. I'd have to say that having used apache 1.3 a lot in the past that for linux hosting, it's quite impressive. Most of what they did was configuration that you could point any ISP to and they'd probably be happy to read it.
Many hosts still run apache 1.3 as well. If it's configured right it can already handle load well, if a tad slower than some of the ultra lightweight speed daemons. There was one on Windows in the day called Xitami. I haven't used windows in about 5 years, but I think it's still maintained. It was unbelievably fast. I had a pentium100 with 64 megs of ram running NT and it flew running php. I had to switch to apache to slow it down because it was always flooding the network around it. Seriously, I went to apache becausewe were already switching to linux and I just had a workstation running windows that I tossed it on for a month. Lighttpd is kind of like that for linux. And I've seen a few others posted about. Check google for 'light weight http server" and such, and you'll find loads of info on them.
But Lighttpd's idea seems brilliant. Instead of connection pooling, it does php backend pooling. It loads up multiple copies of php in the background, and invokes them from a small pool as needed. The key is, if you can grab one and serve a page quickly, you won't need 5,000 copies of php sitting in memory. While multiple copies of code each used shared space in memory, their stacks and data structures are their own. You might have a few hundre http daemons, and 25-50 php backends each with persistant connections, each with the machine allocated and ready to run, sitting at idle.
Meanwhile, apache launches a new php process for each page it has to serve via php.
With something like Lighttpd, you don't have to do that, because if a page has no php, it uses a child process (pre-spawned) to just grab the image and go, and if it does have php, there's a good chance it will grab a "live" backend that already has most of the code you need sitting in it.
If you ask me, that's a simple yet ingenious design for a php / web server. I haven't test it out much but to just get it running. But I'd like to write some database apps and benchmark them.
