CODEWITHSUNDEEP
javagarbage-collection
Eleco
Eleco

Reputation: 3254

OldGen usage goes up after Full GC

Trying to debug a memory leak in a java program (running on linux 64bits), using VisualVM 1.3.

I noticed that after each click on the "Perform GC" button in the VisualVM Monitor tab, the "used" value for the Old Gen memory pool goes up... which seems rather counter-intuitive...

That would make sense if "Perform GC" did trigger a GC for the young gen only (since some objects could then be migrated from young to old gen)... But not in the case of a full GC.

Has anyone has encountered this before ? Thanks.

Eg. 1) OldGen Initial state:

PeakUsage committed:1431 Mb init:1431 Mb max:1431 Mb used:98Mb

Usage committed:1431 Mb init:1431 Mb max:1431 Mb used:98Mb

2) Perform GC

3) New state:

PeakUsage committed:1431 Mb init:1431 Mb max:1431 Mb used:105Mb

Usage committed:1431 Mb init:1431 Mb max:1431 Mb used:105Mb

Upvotes: 1

Views: 491

Answers (1)

Mike Tunnicliffe
Mike Tunnicliffe

Reputation: 10782

It seems quite possible that full GC could also cause migration of young gen objects to the old gen. Do you have some specific reason to think otherwise?

Upvotes: 2

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