Re: [Exist-development] Strange NPE....

[Andrzej J. T. <an...@ch...>]

Wolfgang:

> java.lang.NullPointerException
> 	at org.exist.stax.EmbeddedXMLStreamReader.verifyOriginNodeId(EmbeddedXMLStreamReader.java:250)
> 	at org.exist.stax.EmbeddedXMLStreamReader.next(EmbeddedXMLStreamReader.java:240)
> 	at org.exist.dom.VirtualNodeSet.addChildren(VirtualNodeSet.java:503)
> 	at org.exist.dom.VirtualNodeSet.getNodes(VirtualNodeSet.java:449)
> 	at org.exist.dom.VirtualNodeSet.realize(VirtualNodeSet.java:567)
> 	at org.exist.dom.VirtualNodeSet.getLength(VirtualNodeSet.java:736)
> 	at org.exist.dom.VirtualNodeSet.isEmpty(VirtualNodeSet.java:646)
> 	at org.exist.xquery.Atomize.atomize(Atomize.java:75)
> 	at org.exist.xquery.Atomize.eval(Atomize.java:66)
> 	at org.exist.xquery.CastExpression.eval(CastExpression.java:95)
> 	at org.exist.xquery.AbstractExpression.eval(AbstractExpression.java:61)
> 	at org.exist.xquery.PathExpr.eval(PathExpr.java:241)
> 	at org.exist.xquery.UserDefinedFunction.eval(UserDefinedFunction.java:137)
> 	at org.exist.xquery.DynamicCardinalityCheck.eval(DynamicCardinalityCheck.java:71)
> 	at org.exist.xquery.UntypedValueCheck.eval(UntypedValueCheck.java:82)
> 	at org.exist.xquery.FunctionCall.evalFunction(FunctionCall.java:274)
> 	at org.exist.xquery.FunctionCall.eval(FunctionCall.java:201)
> 	at org.exist.xquery.GeneralComparison.genericCompare(GeneralComparison.java:501)
> 	at org.exist.xquery.GeneralComparison.genericCompare(GeneralComparison.java:494)
> 	at org.exist.xquery.GeneralComparison.eval(GeneralComparison.java:449)
> 	at org.exist.xquery.AbstractExpression.eval(AbstractExpression.java:61)

>
> It looks like some inconsistency in the persistent DOM of the
> document. I would suggest to run the consistency checker to see if it
> reports any issues.

I don't think it's a persistent DOM problem...for a couple of reasons:

1) Rerunning the exact same job, that traverses the identical data, does not consistently throw this exception. If there
was a DOM issue, I think it would die consistently, non?

2) Looking at the code where it died, the line in EmbeddedXMLStreamReader.verifyOriginNodeId() that NPE'ed is:

	origin.setInternalAddress(StoredNode.UNKNOWN_NODE_IMPL_ADDRESS);

   but the two lines before that are:

	if (!nodeId.equals(origin.getNodeId())) {
	    LOG.warn("expected node id " + origin.getNodeId() + ", got " + nodeId + "; resyncing address");

   the only way for line 250 to NPE would be if origin was null.  But if origin was null, then it should have NPE'ed in
   the if or LOG statements first!

   The conclusion is that there is a concurrency issue somewhere....and orgin was changed from a valid value to null
   by another thread sometime between the LOG statement and before line 250.

Any thoughts or ideas?

Thanks!

-- 
Andrzej Taramina
Chaeron Corporation: Enterprise System Solutions
http://www.chaeron.com