http://public.yahoo.com/~radwin/talks/yahoo-phpcon2002.htm Please go give it a look if you like. It said yahoo is using FreeBSD,MySQL, and between java solution and php, they think java has problem with the thread limition. I am a java guy, so I don't know how does php get around this issue. I know there is a limited about the number of processes running in a Linux OS and BSD. Can any body let me know how to solve it and why does not php have the same problem?