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javamelody: monitoring of JavaEE applications

http://code.google.com/p/javamelody/

The goal of JavaMelody is to monitor Java or Java EE applications 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 help to:

* give facts about the average response times and number of executions
* make decisions when trends are bad, before problems become too
serious
* optimize based on the more limiting response times
* find the root causes of response times
* verify the real improvement after optimizations

It includes summary charts showing the evolution over time of the following indicators:

* Number of executions, mean execution times and percentage of
errors of http requests, sql requests or methods of business
façades (if EJB3 or if Spring)
* Java memory
* Java CPU
* Number of user sessions
* Number of jdbc connections

These charts can be viewed on the current day, week, month or year.

JavaMelody includes statistics of predefined counters (as of today http requests, sql requests and methods of business façades if EJB3 or if Spring) with, for each counter :

* A summary indicating the overall number of executions, the average
execution time, the cpu time and the percentage of errors.
* And the percentage of time spent in the requests for which the
average time exceeds a configurable threshold.
* And the complete list of requests, aggregated without dynamic
parameters with, for each, the number of executions, the mean
execution time, the mean cpu time, the percentage of errors and an
evolution chart of execution time over time.
* Furthermore, each http request indicates the size of the flow
response, the mean number of sql executions and the mean sql time.

It also includes statistics on http errors, on warnings and errors in logs and on data caches if ehcache.

An optional and independent collect server may be used if necessary to unload the application of storage management, and of reports generation and to centralize the data of clustered applications or of several applications.