GC Summary Panel

This display shows a collection of statistical information about your garbage collector trace captured with the -Xverbosegc or -Xloggc option. These measures are organized into three major sections:  Heap Capacity, GC Activity Summary, and Overall Statistics.

Heap Capacity

This area of the summary display shows capacity information about the Java heap and its components at the beginning and ending of the application, and the peak capacity of each components, along with percentage of the peak utilization of these components. 

A rule of thumb for optimal utilization would be to have the Eden space at 100% with the Survivor and Old spaces showing some reserve capacity depending on the application.

GC Activity Summary

This table presents various summary statistics for each type of garbage collection event.  The value in the last column, Average rate of collection, can show a dramatic difference in the performance of different garbage collection event types.

Overall Statistics

This area presents various statistics about the measurement taken: