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Hash Entries throwing Java_Version error [message #1410845]

Thu, 21 August 2014 19:31

Rob Latham

Messages: 1
Registered: July 2009

Junior Member

When I try to examine a HashMap using any of the Java Collections tools I get the following error:

Field 'java_version' of 'class sun.misc.Version @ 0x7e016e2b0' contains an illegal object reference: 0x7e016e318
Field 'java_version' of 'class sun.misc.Version @ 0x7e016e2b0' contains an illegal object reference: 0x7e016e318
Object 0x7e016e318 not found.
Object 0x7e016e318 not found.

Has anyone else seen this, or have an idea how to fix it?

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Re: Hash Entries throwing Java_Version error [message #1450349 is a reply to message #1410845]

Wed, 22 October 2014 11:00

Andrew Johnson

Messages: 125
Registered: July 2009

Senior Member

I haven't seen that particular problem, but it ends up being an occasional problem with some dumps and queries.

When MAT builds the indices it reads through the dump finding all the objects, then sorts the addresses and gives each one an ID. It then reads through the dump again and builds the outbound references. It is possible that an outbound reference isn't a known object. It won't be listed as an outbound reference. Then later when a query runs and a field is read then it is possible that it is an address not known as an object.

The query could be changed to handle this case. Perhaps the index building step should add unknown addresses as a dummy objects, though this could make the index building take even longer as even the initial scan would have to look at all the outbound references. A more complex compromise would be to maintain a list of unknown addresses, then reindex to insert those addresses (rather like unreachable objects are removed from the indices).

Andrew Johnson

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