RFR: 6823565: Excessive use of HandleList class in de-serialization code causes OutOfMemory

[Claes Redestad]

Hi,

when deserializing objects with references to themselves, 
ObjectInputStream pointlessly marks the object as a dependency of 
itself, which increases memory required to deserialize certain memory 
graphs.

bug: https://bugs.openjdk.java.net/browse/JDK-6823565
webrev: http://cr.openjdk.java.net/~redestad/6823565/webrev.01/

Testing: jtreg java/io; verified memory allocation/usage drops when 
reading self-referencing objects.

/Claes