PermGen was removed and replaced with MetaSpace.

  Class and metadata moved to MetaSpace.

  MetaSpace is not contiguous with Java Heap and allocated out of Native memory.

  This means it can use available memory from the system upto max memory until

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MetaSpace size max limit can be configured using JVM options.

G1 starts supporting the concurrent unloading of Classes.

Code Cache is introduced. It stores compiled code by the JIT compiler.

Compressed Class Space is also introduced.