-XX:[+|-]HitachiVerboseGCPrintTenuringDistribution (Age distribution output option of Survivor area)

Format

-XX:+HitachiVerboseGCPrintTenuringDistribution

This option specifies that the age distribution of the Survivor area is to be output to the JavaVM log file.

-XX:-HitachiVerboseGCPrintTenuringDistribution

This option specifies that the age distribution of the Survivor area is not to be output to the JavaVM log file.

To Page Top

Description

Specify whether to output the age distribution of the Survivor area to the JavaVM log file.

Default value

• -XX:-HitachiVerboseGCPrintTenuringDistribution

Prerequisite options

• -XX:+HitachiVerboseGC

Related option

• -XX:+HitachiVerboseGCPrintDate

• -XX:+HitachiCommaVerboseGC

To Page Top

Output format

[id]date[Desired survivor:size bytes][New threshold:value][MaxTenuringThreshold: max_value][age1:total_age1][age2:total_age2]...[agen:total_agen]

The following is a description of the output contents:

id

PTD (JavaVM log file identifier).

date

Indicates the date and time for starting GC.

size

Indicates the object target size in Survivor area after GC.

value

Specifies the tenuring threshold value of the Java objects promoted to the Tenured area during the next copy GC.

This value is set up dynamically for each copy GC, based on the values specified in the -XX:MaxTenuringThreshold=value option, the memory size of the Survivor area, and the -XX:TargetSurvivorRatio=value option.

The tenured Java objects more than the value in value are promoted to the Tenured area in the next copy GC.

max_value

Maximum (value specified in the MaxTenuringThreshold option) tenuring threshold value (value) of the Java objects promoted to the Tenured area during copy GC.

The value is set up dynamically for each copy GC; however, does not exceed the max_value value.

Also, the Java objects for which tenuring is greater than the max_value value are definitely promoted to the Tenured area during the next copy GC.

total_age1

Indicates total number of bytes of a 1 year old object.

total_age2

Indicates total number of bytes of a 1 to 2 year old object.

total_agen

Indicates total number of bytes of a 1 to n year old object.

If n is close to max_value, it means that an object with a long life exists.

To Page Top

Examples of output

[PTD]Wed Jan 28 17:47:10 2009[Desired survivor:32768 bytes][New threshold:30][MaxTenuringThreshold:30][age1:6872][age2:9632][age3:25632]

To Page Top