Permgen - part of the heap or not?

Question

I found an image from the oracle official site

but in the popular SO answer I found that the constant generation is not part of the heap

Permanent generation (not a bunch): a pool containing all the reflective data of the virtual machine itself, such as a class and method objects. With Java virtual machines using class sharing, this generation is divided into read-only and read-write areas.

I messed up this conflicting data. I believe that in both places the data is valid, but with reservations. Please clarify this question for me.

PS

talk only about Sun / Oracle jvms.

PS2

jvm gcs (serial, parallel, cms g1), , , .

Answer 1

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Oracle

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• Oracle GC.
• Oracle GC

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Answer 2

Java 8 PermGen, MetaSpace , .

Java <= 7 PermGen, Java, , . 32 CompressOops, . .

, , PermGen/MetaSpace .

, ,

java.lang.OutOfMemoryError: Heap space space

, PermGen, .

java.lang.OutOfMemoryError: PermGen space

https://plumbr.eu/outofmemoryerror/java-heap-space

https://plumbr.eu/outofmemoryerror/permgen-space

https://plumbr.eu/outofmemoryerror/metaspace

Answer 3

Permgen - Java 7 . Java 8 ( ). , :

• hotshot jrockit
• 'java.lang.OutOfMemoryError: PermGen' , -

Memory objects that have occurred in permgen have been placed in metaspace since Java 8. Metaspace resizes the memory area and is placed in a heap.