jdbm / Bugs / #7 BTree java.io.OptionalDataException

#7 BTree java.io.OptionalDataException

Status: open

Owner: Alex Boisvert

Labels: None

Priority: 5

Updated: 2001-11-13

Created: 2001-11-08

Creator: Nathan Clement

Private: No

I have set up a test for JDBM which simulates its
intended use in our messaging system. This usage
involves storing messages while they are being
processed, updating them a few times, then removing
them from the storage area.

I have 2 BTrees set up - one which stores the message
itself (updated fairly infrequently) and one which
stores the message statuses (updated more frequently).

The test runs quite well for 200 or so messages, then
I start getting exceptions when using the BTree
object. They occur on either insert or remove
operations.

I am running Sun JDK 1.3.1 on Windows 2000.

java.io.OptionalDataException
at java.io.ObjectInputStream.readObject
(ObjectInputStream.java:411)
at java.io.ObjectInputStream.readObject
(ObjectInputStream.java:236)
at jdbm.btree.BPage.readExternal
(BPage.java:723)
at java.io.ObjectInputStream.inputObject
(ObjectInputStream.java:1212)
at java.io.ObjectInputStream.readObject
(ObjectInputStream.java:386)
at java.io.ObjectInputStream.readObject
(ObjectInputStream.java:236)
at jdbm.recman.RecordManager.byteArrayToObject
(RecordManager.java:294)
at jdbm.recman.RecordManager.fetchObject
(RecordManager.java:236)
at jdbm.helper.ObjectCache.fetchObject
(ObjectCache.java:104)
at jdbm.btree.BTree.getRoot(BTree.java:452)
at jdbm.btree.BTree.remove(BTree.java:308)

Discussion

Alex Boisvert - 2001-11-13

assigned_to: nobody --> boisvert
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Alex Boisvert - 2001-11-14

Synthetic test case

Broker.java

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Alex Boisvert - 2001-11-14

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user_id=982

I have been unable to reproduce this bug so far. I've
written a test case which simulates the insertion and
removal of messages in one BTree and the insertion, update
and removal of message status in another BTree.

See attached example.

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Nathan Clement - 2001-11-15

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user_id=310643

I have tried to write a test case that reproduces the
problem, but have not been successful. I have attached a
file which simulates more accurately the test that I set
up. The actual application uses mulitple threads to
process the message, but the test program uses only a
single thread. I set up the messaging application in a
loop-back mode, with a single message travelling around
repeatedly. The steps in the example program show the
relevant steps in our application. Note that I was using
the record manager with transactions disabled, if that
makes any difference.

I'm sorry that I can't provide any more information - I
can't really send the source code to our whole messaging
application, and I can't seem to reproduce the problem
outside that environment. Because of the workaround I
spoke about earlier, I wouldn't complain if we just dropped
the issue.

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Nathan Clement - 2001-11-15

Updated test case (still does not reproduce error)

Broker2.java

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BTree java.io.OptionalDataException

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#7 BTree java.io.OptionalDataException

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