Using GCViewer For GC Analysis

GCViewer developed by Tagtraum Industries is one of the free tools that you can use to visually analyse the garbage collection logs.

Running GCViewer

The latest version is now maintained by chewiebug and available for download at http://sourceforge.net/projects/gcviewer/files/

• Download the gcviewer-x.xx.jar to your local system
• Launch the viewer by running java -jar path_to_gcviewer-x.xx.jar
• You need Java version >= 1.7

Using GCViewer

• Open the GC log file from the test run using GCViewer
• Adjust the zoom levels (dropdown at the top) so that the graph fits the window and there are no scroll bars (to get an overview)

• Check the trend of the 'Total Heap' usage of the VM. As long as it does not show an upward trend, VM is considered to be fine.
• Check the right side of the tool for the information related to the run - Summary, Memory and Pause.

Summary

• 'Number of full gc pauses' are of concern and healthy VM should not generally be doing a full GC (which means it should ideally be zero). Full GCs result in the VM being inactive till the GC completes.

Memory

• The 'Total heap' gives an indication on how much the VM memory is loaded.

Pause

• Total time spend on 'gc pauses' is of interest.