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Now I trying to understand fundamental concepts of java garbage collection.

I have read a lot articles about it.

And somewhere I see old generation and somewhere tenured generation. Description is very similar.

looks like one of them is the evolution of second.

Can you provide more information about this topiс?

gstackoverflow
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2 Answers2

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I've always regarded the Old Generation and Tenured Generation as the same thing, and this diagram from http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/gc01/index.html backs that up.

enter image description here

if you Google Old generation versus Tenured you'll also find lots of people saying things like "Tenured (Old) Generation" -like http://www.javaspecialists.eu/archive/Issue092.html

Occasionally, I've seen people regard Old Generation as the Tenured + Permanent Generation but I've never seen any official confirmation for that.

matt freake
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  • *"... but I've never seen any official confirmation for that."* - Not surprising. I don't think is is true. In Java 7 and earlier, the Old generation and Permgen were separate. And in Java 8 and onwards, permgen is replaced with the "metaspace" – Stephen C Oct 20 '14 at 11:08
  • @Disco 3 and what the reason to call same thing by different names? – gstackoverflow Oct 20 '14 at 11:40
  • I'm afraid I don't know the reason for the difference. – matt freake Oct 21 '14 at 08:11
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Anyway the Permanent Generation is moved to native space and is out of GC competence in Java 8. So now it seems to be the same.

Simon
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