Diagnostic Tool for Java Garbage Collector

The Diagnostic Tool for Java Garbage Collector is a diagnostic tool for optimizing parameters affecting the garbage collector when using the IBM® Java virtual machine (JVM).

Applications that run under Java™ use what is known as a Java heap for garbage collection, which serves as a storage manager in Java development kits provided by IBM and runtime environments.

An analysis of data reflecting the activity of the garbage collector in Java enterprise or stand-alone applications is critical to optimizing tasks running under a JVM. For example, you must consider the following issues when you optimize parameters for Java applications and try to prevent bottlenecks:
  • the frequency of the garbage collection cycle
  • the time spent in different phases of the garbage collection
  • the quantities of heap memory involved in the process
  • the characteristics of the allocation failures from which the garbage collection originate
  • the unwanted presence of stack overflows

Diagnostic Tool for Java Garbage Collector helps to examine the characteristics of the garbage collection for an application running under a JVM by reading the output of the "verbose" garbage collection and producing textual and graphical visualizations and related statistics. This tool is well suited for looking at the garbage collector activity of a frequently-accessed enterprise application hosted by a WebSphere® Application Server. The tool includes a "multiple file analysis" modality that allows the loading of two or more files simultaneously, thereby enabling you to compare the behavior of two or more application servers in a WebSphere cluster.

Diagnostic Tool for Java Garbage Collector Version 1.3 comes with the following built-in parsers and sample files so you can evaluate features of the tool and review documentation:
  • IBM JVM Version 1.5.0
  • IBM JVM Version 1.5
  • IBM JVM Version 1.2.2
Each parser is likely to be able to parse the data that is produced by some other versions of the IBM JVM; for instance, the JVM Version 1.5 parser also works well with the JVM Version 1.3.x. For unsupported versions of the IBM JVM, the tool contains detailed documentation that allows one to code a different parser in Java by implementing the GCParser interface. The documentation describes in detail the assumptions and the rules necessary for coding of the new parser