Some suggestions:
- Perf4J: Perf4J is a set of utilities for calculating and displaying performance statistics for Java code.
- ERMA: ERMA (Extremely Reusable Monitoring API) is an instrumentation API that has been designed to be applicable for all monitoring needs.
- javasimon: Java Simon is a simple monitoring API that allows you to follow and better understand your application. Monitors (familiarly called Simons) are placed directly into your code and you can choose whether you want to count something or measure time/duration.
- Glassbox: The Glassbox troubleshooter is an automated troubleshooting and monitoring agent for Java applications that diagnoses common problems with one-click.
- InfraRED: InfraRED is a tool for monitoring performance of a Java EE application and diagnosing performance problems. It collects metrics about various aspects of an application’s performance and makes it available for quantitative analysis of the application.