9.11.2 Output format and output example of the tenuring distribution information of the Survivor area
The tenuring distribution information of the Survivor area is output following to the log of the copy GC when the copy GC occurs. The output format and the output example of the tenuring distribution information of the Survivor area are as follows:
- Output format
[PTD]<date>[Desired survivor:size bytes][New threshold:value][MaxTenuringThreshold: max_value][age1:total_age1][age2:total_age2]...[agen:total_agen]
Description
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PTD: An identifier that indicates the tenuring information of the Survivor area
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Date: Date and time when GC occurred (outputs only when -XX:+HitachiVerboseGCPrintDate (extended verbosegc information date output option) is specified)#1
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size: Size of the Survivor area (unit: bytes)
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value: Tenuring threshold value of the object that migrates to the Tenured area when the GC will occur next time
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max_value: Specified value of -XX:MaxTenuringThreshold#2
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total_age1: Total of memory size used by the one-year-old object (unit: bytes)
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total_age2: Total of memory size used by the one-to-two-year-old object (unit: bytes)
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total_agen: Total of memory size used by the object from 1-year-old to n-year-old (unit: bytes)#3
- Note:
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When -XX:+HitachiCommaVerboseGC is specified, the tenuring
distribution information is output in the following format:
PTD,date,size,value,max_value,total_age1,total_age2,...,total_agen
- #1
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The time similar to the log of the corresponding copy GC is displayed.
- #2
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Set the threshold value of the frequency in which the Java object is replaced in the From space and in the To space when executing the copy GC in the specified value of the -XX:MaxTenuringThreshold.
- #3
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The existing object is displayed in the order from minimum years to the maximum years. If the maximum years of the displayed object are nearer to the value of max_value, then the object with long life exists is indicated.
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- Example of output
[VGC]<Wed May 28 11:45:23 2008>[GC 648K->136K(1984K), 0.0013020 secs][DefNew::Eden: 512K->0K(512K)][DefNew::Survivor: 0K->0K(64K)][Tenured: 136K->136K(1408K)][Metaspace: 3634K(4492K, 4492K)->3634K(4492K, 4492K)][class space: 356K(388K, 388K)->356K(388K, 388K)][cause:ObjAllocFail][User: 0.0000000 secs][Sys: 0.0000000 secs] [PTD]<Wed May 28 11:45:23 2008>[Desired survivor:5467547 bytes][New threshold:30][MaxTenuringThreshold:31][age1:1357527][age2:1539661]
You can check the following contents in the above output example:
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The output trigger is a copy GC that occurred at 11:45:23 on Wednesday, May 28, 2008.
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The memory size of the Survivor area is 5,467,547 bytes. The object of the Survivor area is of up to two years old. The memory size used by the one-year-old object is 1,357,527 bytes, and the memory size used by the object from one-year-old to two-year-old, is 1,539,661 bytes.
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