ON THIS LINK

A good way to see how your Web applications and server will behave under high load is by testing them with a simulated load. We tested several free software tools that do such testing to see which work best for what kinds of sites. If you leave out the load-testing packages that are no longer maintained, non-free, or fail the installation process in some obscure way, you are left with five candidates: curl-loader, httperf, Siege, Tsung, and Apache JMeter.