I am trying to upgrade my webapp to Java6 and Tomcat6. I successfully upgraded it on a test server and am testing it using JMETER. I am testing the old configuration (Java1.4 and Tomcat5) vs new configuration (Java1.6 and Tomcat6). I noticed that the performance was bad with the new configuration.
Do I need to make an changes in my code to work well in Java6 (developed using java1.4)?.
As I recall, Tomcat6 was reputed to be notably faster than Tomcat5. Tomcat5 was unfortunate enough to be stuck in the middle of the transition from the old (1.4 and earlier) JVMs to the new 1.5+ JVMS, where a lot changed, and it shows - there's 2 separate 5.x release chains, one for Java 1.x (5.0) and one for Java 5+ (5.5).
Tomcat 6 no longer had to retain vestiges of backwards compatibility with Java 1.4, plus they did some general cleanup, so I'd expect it to do better overall. I never saw any hard numbers, but certainly I never felt any pain moving up myself.
Customer surveys are for companies who didn't pay proper attention to begin with.