7.6.9 -XX:[+|-]HitachiVerboseGCPrintTenuringDistribution
-XX:[+|-]HitachiVerboseGCPrintTenuringDistribution outputs the age distribution for the Survivor area to the Java VM log file.
Description
-XX:[+|-]HitachiVerboseGCPrintTenuringDistribution specifies whether the Survivor area age distribution that is output when -XX:+PrintTenuringDistribution is specified, is to be output to the Java VM log file.
- Prerequisite option
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-XX:+HitachiVerboseGC
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- Related options
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-XX:+PrintTenuringDistribution
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-XX:+HitachiVerboseGCPrintDate
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-XX:+HitachiCommaVerboseGC
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- Format of output
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[id]<date>[Desired survivor:size bytes][New threshold:value] [MaxTenuringThreshold: max_value][age1:total_age1][age2:total_age2]... [agen:total_agen]
The following provides details about the output.
Output item
Output content
id
PTD (Java VM log file identifier)
date
Start date and time of GC
size
Target size of the objects in the Survivor area after GC
value
Age threshold for Java objects that are to be promoted to the Tenured area in the next CopyGC.
This value is dynamically set for each CopyGC, based on the values set for the -XX:MaxTenuringThreshold=value option, the memory size of the Survivor area, and the -XX:TargetSurvivorRatio=value option.
The Java objects whose age is equal to or greater than value will be promoted to the Tenured area in the next CopyGC.
max_value
Maximum value (value specified for the MaxTenuringThreshold option) of the age threshold (value) for the Java objects that are to be promoted to the Tenured area in the CopyGC.
value is dynamically set for each CopyGC but cannot exceed max_value.
The Java objects whose age is equal to or greater than max_value will always be promoted to the Tenured area in the next CopyGC.
total_age1
Total size (in bytes) of 1-year-old objects.
total_age2
Total size (in bytes) of 1-to 2-year-old objects.
total_agen
Total size (in bytes) of 1-to n-year-old objects.
If n is close to max_value, it means that an object with a long life exists.
Syntax
-XX:[+|-]HitachiVerboseGCPrintTenuringDistribution
Specifiable values
Type: String
- -XX:+HitachiVerboseGCPrintTenuringDistribution
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Outputs the Survivor area age distribution that is output when -XX:+PrintTenuringDistribution is specified, to the Java VM log file.
- -XX:-HitachiVerboseGCPrintTenuringDistribution
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Does not output the Survivor area age distribution that is output when -XX:+PrintTenuringDistribution is specified, to the Java VM log file.
Example
[PTD]<Wed Jan 28 17:47:10 2009>[Desired survivor:32768 bytes][New threshold:30] [MaxTenuringThreshold:30][age1:6872][age2:9632][age3:25632]
Notes
The amount of log data that is output during CopyGC when this option is specified is two or more times the amount of data that is output when this option is not specified.
For this reason, use this option only for tuning purposes.