http://jrat.sourceforge.net/ JRat is the Java Runtime Analysis Toolkit. Its purpose is to enable developers to better understand the runtime behavior of their Java programs. There are currently a number of ways JRat can monitor an application (i.e. Bytecode instrumentation, JBoss AOP, Dynamic Proxies, JDI).
http://besee.sourceforge.net/ beSee 2 provides a mechanism to plug a class preprocessor instrumentation layer in any classloader hierarchy, thus supporting java 1.3, 1.4, J2SE and J2EE environment. beSee 2 is the ground 0 lightweight layer of the next generation AOP architecture. It provides a bytecode kit independant solution and comes ready to use with two implementation: BCEL and Javassist.
http://fprofiler.sourceforge.net/ FProfiler is a Java Profiler using BCEL and log4j. Its very fast because it inserts the needed instructions into the Bytecode of the classes. It can be used to find Hotspots in Java programs, libs and servlet environments simply every Java class.
http://sourceforge.net/projects/jamonapi/ JAMon API is a free, simple, high performance, thread safe, Java API that allows developers to easily monitor the performance and scalability of production applications. JAMon tracks hits, execution times (total, avg, min, max, std dev), and more.
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