GC Analyzer

Analysis of VerboseGC Traces

Contents

News
Download
GCA
Future
Support
GCA Manual
Javadoc

The Garbage Collection Analyzer (GCA) tool parses through verbosegc output of a Java virtual machine (JVM) in order to present it in a more meaningful way.

News

February 24, 2005	Posted GCA 0.4.0 - Added JDK 1.4.2 support, minor GUI enhancements, persistent user preferences remember which trace you viewed last, text summary displays beginning and ending trace times and percent GC.
February 11, 2005	Posted GCA 0.3.1 - Added JDK 1.4.1 support. This was trivial since 1.4.1 and 1.3.1 have same verbosegc format.
February 9, 2003	Posted GCA 0.3.0 - Added file browser to trace file entry field.
February 2, 2003	Posted GCA 0.2.1 - Patched a bug for cases where the number of data points exceeded the number of pixels.
January 10, 2003	Posted GCA 0.2.0. - Now the verbosegc trace file and jdk type are specified through a GUI. It's still very rough though.
January 1, 2003	Posted GCA 0.1.0. - This is the initial get-it-out-quick version. All options are specified at the command line.

Download

gca.zip - JAR libraries plus API docs. About 190 KB.
gcasrc.zip - GCA source code. About 90 KB.

GCA

The GCA tool processes verbosegc output by storing the records internally to summarize them statistically. These summaries are referred to as views into the verbosegc. Presently there are only two views: a text summary and a graphical histogram. A sample text view is show below.

Summary First GC time: Wed, Feb 09, 08:43:40 PST Last GC time: Wed, Feb 09, 12:34:11 PST Total GCs: 395 Total GC Time: 27571 msec Average GC Time: 69 msec Percent GC Time: 0% Compactions: 3 Max GC time: 112 msec on Wed Feb 09 10:49:48 PST 2005

A histogram from the same sample run looks like

Histogram

The Future

Here are some features I'm either contemplating or working on.

The ability to export the histogram in a graphics format such as JPG, GIF or PNG. Unfortunately, the standard APIs for this are only included in JDK 1.4. I'm not sure how I want to introduce such a dependency at this stage. Perhaps I can programmatically make this feature available only if running a Java 1.4 JDK.
Better API documentation for those who wish to extend GCA for themselves.
Detect and count the number of manual GCs (those that do not result from allocation failures).

Support

If you have any questions about GCA, feel free to email me at "pglezen at us dot ibm dot com". I can't gaurantee a timely response since I work on this on my own time. But I am interested in feedback.