unit/T_RawStoreFactory.unit fails with an assert failure in J2ME/CDC/FP

[Deepa Remesh <dr...@gmail.com>]

The test unit/T_RawStoreFactory.unit fails with an assert failure in
CDC/FP. This failure looks like an intermittent one though it is
failing all the time now. I have run this test successfully some time
back. I would like to find out if this is a bug (Derby or jvm) or just
an intermittent failure. I am using j9 foundation from IBM WCTME5.7.

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diff for the test:
---------------------------------------------------------------------
 < -- Unit Test T_RawStoreFactory finished
 2 add
 > There should be 0 observers, but we still have 1 observers.
> Shutting down due to unit test failure.
---------------------------------------------------------------------
stack trace for AssertFailure in derby.log is:
---------------------------------------------------------------------
 FAIL - org.apache.derby.iapi.services.sanity.AssertFailure: ASSERT
FAILED still on observer list
org.apache.derby.impl.store.raw.data.TruncateOnCommit@f147d525
org.apache.derby.iapi.services.sanity.AssertFailure: ASSERT FAILED
still on observer list
org.apache.derby.impl.store.raw.data.TruncateOnCommit@f147d525
	at org.apache.derby.iapi.services.sanity.SanityManager.THROWASSERT(SanityManager.java:150)
	at org.apache.derby.impl.store.raw.data.TruncateOnCommit.update(TruncateOnCommit.java:69)
	at java.util.Observable.notifyObservers(Observable.java:117)
	at org.apache.derby.iapi.store.raw.xact.RawTransaction.notifyObservers(RawTransaction.java:313)
	at org.apache.derby.impl.store.raw.xact.Xact.doComplete(Xact.java:1927)
	at org.apache.derby.impl.store.raw.xact.Xact.preComplete(Xact.java:1880)
	at org.apache.derby.impl.store.raw.xact.Xact.prepareCommit(Xact.java:726)
	at org.apache.derby.impl.store.raw.xact.Xact.commit(Xact.java:839)
	at org.apache.derby.impl.store.raw.xact.Xact.commit(Xact.java:636)
	at org.apache.derbyTesting.unitTests.store.T_Util.t_commit(T_Util.java:838)
	at org.apache.derbyTesting.unitTests.store.T_RawStoreFactory.TC001(T_RawStoreFactory.java:7435)
	at org.apache.derbyTesting.unitTests.store.T_RawStoreFactory.runTempTests(T_RawStoreFactory.java:420)
	at org.apache.derbyTesting.unitTests.store.T_RawStoreFactory.runTestSet(T_RawStoreFactory.java:247)
	at org.apache.derbyTesting.unitTests.harness.T_MultiIterations.runTests(T_MultiIterations.java:94)
	at org.apache.derbyTesting.unitTests.harness.T_MultiThreadedIterations.runTests(T_MultiThreadedIterations.java:91)
	at org.apache.derbyTesting.unitTests.harness.T_Generic.Execute(T_Generic.java:117)
	at org.apache.derbyTesting.unitTests.harness.BasicUnitTestManager.runATest(BasicUnitTestManager.java:183)
	at org.apache.derbyTesting.unitTests.harness.BasicUnitTestManager.runTests(BasicUnitTestManager.java:245)
	at org.apache.derbyTesting.unitTests.harness.BasicUnitTestManager.boot(BasicUnitTestManager.java:92)
	at org.apache.derby.impl.services.monitor.BaseMonitor.boot(BaseMonitor.java:2008)
	at org.apache.derby.impl.services.monitor.TopService.bootModule(TopService.java:290)
	at org.apache.derby.impl.services.monitor.BaseMonitor.bootService(BaseMonitor.java:1846)
	at org.apache.derby.impl.services.monitor.BaseMonitor.startServices(BaseMonitor.java:966)
	at org.apache.derby.impl.services.monitor.BaseMonitor.runWithState(BaseMonitor.java:398)
	at org.apache.derby.impl.services.monitor.FileMonitor.<init>(FileMonitor.java:59)
	at org.apache.derby.iapi.services.monitor.Monitor.startMonitor(Monitor.java:288)
	at org.apache.derbyTesting.unitTests.harness.UnitTestMain.main(UnitTestMain.java:50)
---------------------------------------------------------------------	

On looking at the code, I did not understand how this assert failure
can happen. The assert is thrown in following code in
TruncateOnCommit:
public void update(Observable obj, Object arg) {
	if (SanityManager.DEBUG) {
		if (arg == null)
		SanityManager.THROWASSERT("still on observer list " + this);
	}

I am puzzled by how 'arg' can become null in this case. As I
understand, 'update' method of each Observer gets called by the
notifyObserver method in java.util.Observable class. notifyObserver
passes 'arg', which describes the type of change, as the second
argument to update. In this code path, 'arg' passed to notifyObserver
is RawTransaction.COMMIT (which is not null).

However the code has an assert to check for null value which means
there is some situation where the 'arg' can become null. Can someone
please explain when this is possible? I would greatly appreciate help
on this.

Thanks,
Deepa