CODEWITHSUNDEEP
jstat
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Noobie

Reputation: 571

Total heap size and used heap jstat does not matches with VISUALVM

I looking for a way to find the HEAP statistics of the given running JVM process.

I have read a SO article related to it.

Firstly I never understood the difference between Heap size the and Used Heap size so (because the Max heap size means the total heap size means the total heap assigned to JVM), if someone can explain it that would be helpful...

moving forward now according to the article the heap used is 

Used heap would be the sum of all the fields that end with
 "U" - S0U, S1U, EU, OU (again, except metaspace)

I tried summing up that value but it seems to match up with find in Visual VM.

Like for example for the following JStat output

{"S0C"=>37440.0, "S1C"=>37440.0, "S0U"=>24834.0, "S1U"=>0.0, "EC"=>187264.0, "EU"=>68714.3, "OC"=>1310720.0, "OU"=>25368.3, "MC"=>44428.0, "MU"=>41513.4, "CCSC"=>6608.0, "CCSU"=>6200.2, "YGC"=>10.0, "YGCT"=>1.194, "FGC"=>2.0, "FGCT"=>0.047, "GCT"=>1.241}

the Used HEAP size is 118916600 B Whereas in Visual VM I see it as 121770608 B

Any idea what is the difference for?

Upvotes: 1

Views: 489

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