The goal of JavaMelody is to monitor Java or Java EE application servers in QA and production environments. It is not a tool to simulate requests from users, it is a tool to measure and calculate statistics on real operation of an application depending on the usage of the application by users.
JavaMelody is opensource (LGPL) and production ready: in production in an application of 25 person years. JavaMelody is easy to integrate in most applications and is lightweight (no profiling and no database).
JavaMelody is mainly based on statistics of requests and on evolution charts.
It allows to improve applications in QA and production and helps to:
This is the greatest tool for application monitoring I've ever used. It is much simpler (and cheaper) than AppDynamics, NewRelic or dynaTrace. Finding bottlenecks takes just minutes. It also has a JMX management and you can expose values monitoring via HTTP. Just plug it in to you Nagios to alert you while performance is dropping.
The community is not wide but helpful.