HPjmeter 4.3 User's Guide

Table 10 Fields Captured in GC Log Data When Using -Xverbosegc print options (continued)
Tenuring threshold - memory allocation that determines how long newborn objects remain in the new generation.%6
Eden sub-space within the new generation, in bytes.These spaces are reported:%7,
%8,
%9
• Before (Occupied before garbage collection)
• After (Occupied after garbage collection)
• Capacity (Current capacity )
Survivor sub-space within the new generation, in bytes. These spaces are reported:%10,
%11,
%12
• Before
• After
• Capacity
Old generation, in bytes. These spaces are reported:%13,
%14,
%15
• Before
• After
• Capacity
Permanent generation, in bytes. These spaces are reported for storage of reflective objects:%16,
%17,
%18
• Before
• After
• Capacity
Total stop-the-world duration, in seconds.%19
Total time used in collection, in seconds.%20
Collecting Allocation Site Statistics for Viewing in HPjmeter
Use one of the following commands to capture allocation site statistics in a file for display in the
HPjmeter garbage collection viewer:
• Using -XX:+PrintAllocStatistics option to enable the Allocation Statistics function
by entering the following:
$ java ... -XX:+PrintAllocStatistics -Xverbosegc[0|1][:file=[filename[,[n][h][d][u][t]]]]
• Sending a signal to the JVM to capture allocation site statistics data at that time:
$ kill -PROF pid
OR
$ kill -21 pid
Data from the opened file is visible in the Allocation Site Statistics (page 185) visualizers. The GC
viewer automatically opens when you open an Xverbosegc file in the HPjmeter console.
Collecting Glance Data for Viewing in HPjmeter
If you have the HP GlancePlus product installed on your HP-UX system, you can run GlancePlus in
adviser mode using the script at /opt/hpjmeter/bin/javaGlanceAdviser.ksh. This script
has three command-line parameters: the pid of the Java process for which you want to collect data,
the name of the output file to receive the data, and the sampling interval, in seconds. Only the first
parameter is required, the second and third are optional. Here is a sample command line to capture
Glance data in a file for display in the HPjmeter garbage collection viewer:
$ /opt/hpjmeter/bin/javaGlanceAdviser.ksh 1234 ga.out.1234
This command collects information about process 1234 using the default sampling interval, and
writes the results to the file ga.out.1234. You can then open this file in the HPjmeter console to
view the data graphically. If you also collected GC information using the -Xverbosegc option,
you can append the Glance data to the GC log file and then use HPjmeter to read the combined
98 Analyzing Garbage Collection Data