Sorry for OFF-topic: Create dummy "Hello, World!" JSP, use Tomcat, execute load-stress simulator(s) from separate machine(s), and measure... don't forget to allocate necessary thread pools in Tomcat (if you have to)... Although such JSP doesn't use any memory, you will see how easy one can go with 5000 TPS (or 'virtually' 50000 concurrent users) on modern quad-cores by simply allocating more memory (...GB) and more Tomcat threads. There is threshold too... repeat it with HTTPD Workers (and threads), same result, although it doesn't use any GC. More memory - more threads - more "keep alives" per TCP...
However, 'theoretically' you need only 64Mb for "Hello World" :)))
