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K.Haest

How can I see the deduplication statistics in the GC Log report?

Hi,

 

We've activated string deduplication (-XX:+UseStringDeduplication) with statistics enabled (

-XX:+PrintStringDeduplicationStatistics) on a G1 gc. In the gc log I find string deduplication info (sample below) but the gceasy report says "Not Reported in the log".
How can I see the deduplication statistics ?

 

2022-01-12T22:42:24.146+0100: 19.292: [GC concurrent-string-deduplication, 1023.8K->618.4K(405.4K), avg 39.6%, 0.0054954 secs]
   [Last Exec: 0.0054954 secs, Idle: 18.3094246 secs, Blocked: 21/0.0035327 secs]
      [Inspected:           18692]
         [Skipped:              0(  0.0%)]
         [Hashed:            5141( 27.5%)]
         [Known:             6386( 34.2%)]
         [New:              12306( 65.8%)   1023.8K]
      [Deduplicated:         6937( 56.4%)    405.4K( 39.6%)]
         [Young:             6937(100.0%)    405.4K(100.0%)]
         [Old:                  0(  0.0%)      0.0B(  0.0%)]
   [Total Exec: 1/0.0054954 secs, Idle: 1/18.3094246 secs, Blocked: 21/0.0035327 secs]
      [Inspected:           18692]
         [Skipped:              0(  0.0%)]
         [Hashed:            5141( 27.5%)]
         [Known:             6386( 34.2%)]
         [New:              12306( 65.8%)   1023.8K]
      [Deduplicated:         6937( 56.4%)    405.4K( 39.6%)]
         [Young:             6937(100.0%)    405.4K(100.0%)]
         [Old:                  0(  0.0%)      0.0B(  0.0%)]
   [Table]
      [Memory Usage: 584.3K]
      [Size: 8192, Min: 1024, Max: 16777216]
      [Entries: 22200, Load: 271.0%, Cached: 0, Added: 22200, Removed: 0]
      [Resize Count: 3, Shrink Threshold: 5461(66.7%), Grow Threshold: 16384(200.0%)]
      [Rehash Count: 0, Rehash Threshold: 120, Hash Seed: 0]
      [Age Threshold: 3]
   [Queue]
      [Dropped: 0]
[GC concurrent-string-deduplication, deleted 0 entries, 0.0000007 secs]

 

Report URL - https://gceasy.io/my-gc-report.jsp?p=c2hhcmVkLzIwMjIvMDEvMTMvLS1nYy5hc2ZkZTJfc3RhbmRhbG9uZV8xLmFjYy5sb2cuMjAyMi0wMS0xMi4yMi00Mi0wNC56aXAtLTE0LTctMjg=&channel=WEB

  • stringdeduplicationmetrics

  • g1gc

  • gcstring

  • gcevents

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Ankita

Hi K.Haest,

 

‘-XX:+UseStringDeduplication’ feature is supported only from Java 8 update 20. If you are running on any older versions of Java, you will not be able to use this feature.

 

Can you please confirm what java version are you using in application?

 

Thanks.

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K.Haest

openjdk version "1.8.0_312"
OpenJDK Runtime Environment (build 1.8.0_312-b07)
OpenJDK 64-Bit Server VM (build 25.312-b07, mixed mode)

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Ram Lakshmanan

Hello K.Haest!

 

 Greetings. We have fixed the issue now. Below is the genereated String DeDuplicate metrics for your GC log. Apologies for the inconvenience. Thanks.

 

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