Debug optimization problem

[Libor]

I'm using Saxon 9.3 EE and for one of the stylesheets I'm getting this
compilation error:

  Cause: Attempt to end document in serializer when elements are unclosed
java.lang.IllegalStateException: Attempt to end document in serializer when elements are unclosed
        at net.sf.saxon.serialize.XMLEmitter.endDocument(XMLEmitter.java:113)
        at net.sf.saxon.event.ProxyReceiver.endDocument(ProxyReceiver.java:110)
        at net.sf.saxon.trace.ExpressionPresenter.close(ExpressionPresenter.java:185)
        at net.sf.saxon.expr.Expression.explain(Expression.java:578)
        at net.sf.saxon.expr.Optimizer.trace(Optimizer.java:351)
        at net.sf.saxon.expr.LetExpression.optimize(LetExpression.java:206)
        at net.sf.saxon.expr.ExpressionVisitor.optimize(ExpressionVisitor.java:230)
        at net.sf.saxon.style.XSLTemplate.optimize(XSLTemplate.java:412)
        at net.sf.saxon.style.PrincipalStylesheetModule.compileStylesheet(PrincipalStylesheetModule.java:814)
        at net.sf.saxon.PreparedStylesheet.setStylesheetDocument(PreparedStylesheet.java:355)
        at net.sf.saxon.PreparedStylesheet.prepare(PreparedStylesheet.java:186)
        at net.sf.saxon.TransformerFactoryImpl.newTemplates(TransformerFactoryImpl.java:132)
        at com.atypon.literatum.util.xml.TransformerCache.instantiateTemplate(TransformerCache.java:151)

I was able to work it around by disabling optimizations
xformFactory.setAttribute(FeatureKeys.OPTIMIZATION_LEVEL, "0");

How can I find what is the real problem? What document is being serialized?
What are those unclosed elements? What steps should I take to debug it?

[Michael Kay]

The problem occurs while outputting the optimiser trace messages, so you
should be able to avoid it by avoiding use of -explain. I would like to have a
copy of the stylesheet that causes the problem so that I can fix it.

[Libor]

Thanks Michael,
you are right, it has something to do with the
FeatureKeys.TRACE_OPTIMIZER_DECISIONS set to Boolean.TRUE. We do not use that
in production, so I re-enabled optimizations and hacked the debug mode to skip
optimizer decisions tracing for this specific transformation.
I will try to strip out all java extension calls and get smallest style sheet
where tracing optimizer decision is still failing.

[Libor]

I've done pruning up to this point
main.xsl:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:transform version="2.0" xmlns:xsl="&lt;span&gt;[http://www.w3.org/1999/XSL/Transform]&lt;/span&gt; (http://www.w3.org/1999/XSL/Transform)">

<xsl:import href="xxx.xsl"/>

<xsl:template match="foo">
<xsl:variable name="bar">
<xsl:apply-imports/>
</xsl:variable>
<xsl:value-of select="$bar"/>
</xsl:template>

</xsl:transform>

xxx.xsl:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:transform version="2.0" xmlns:xsl="&lt;span&gt;[http://www.w3.org/1999/XSL/Transform]&lt;/span&gt; (http://www.w3.org/1999/XSL/Transform)">

<xsl:template match="foo">
<xsl:value-of select="'x'"/>
</xsl:template>

</xsl:transform>

This is still causing the "java.lang.IllegalStateException: Attempt to end
document in serializer when elements are unclosed" when tracing of optimizer
decisions is enabled.

[oneil]

Hi,

This problem has already been fixed in the Saxon release version 9.3.0.5.
Please see the bug ID: 3184807).

I am not sure which version you are currently running but if you do an upgrade
to 9.3.0.5 then you should be OK.

[Libor]

Thanks, we will try that.