You can execute the class-wise statistical functionality to output the class-wise statistical information to the extended thread dump. In the pre-statistical garbage collection selection functionality, you can select the processing that is to be executed before the class-wise statistical information is output. By selecting this processing that is to be executed, you can acquire the various changes in the appearance of the Java object in the class-wise statistical information, depending on the purpose of investigation.

When using the pre-statistical garbage collection selection functionality, specify the processing to be executed by an argument of the jheapprof command. The following table lists the process and the arguments of the jheapprof commands that can be implemented before executing the class-wise statistical functionality.

Table 9-13 Process and the arguments of the jheapprof commands that can be implemented before executing the class-wise statistical functionality

Type of process	Process contents	Argument of the jheapprof command
Execution of a full garbage collection	Collects the used object for an entire JavaVM specific area even including Tenured area.	-fullgc
Execution of a copy garbage collection	Collects the used object only for the Eden area and for the Survivor area	-copygc
No execution of a garbage collection	Does not collect the used object though available.	-nogc

Note that if you execute the class-wise statistical functionality when specifying -XX:+HitachiVerboseGC and -XX:+HitachiVerboseGCPrintCause in the JavaVM start option, the following information is output to extended verbosegc information:

• Type of garbage collection
• Cause for garbage collection occurrence in the extended thread dump

The above information differs with the information output by an argument specified in the jheapprof command. The following table lists the relation between the arguments of the jheapprof command and the output information.

Table 9-14 Relation between the arguments of the jheapprof command and the output information

Argument of the jheapprof command	Type of garbage collection	Cause for garbage collection occurrence
-fullgc	FullGC	JHeapProf Command
-copygc	GC	JHeapProf Command