DO NOT REPLY [Bug 15320] New: - DTMManager.getDTM(int) sometimes returns null for RTF

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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=15320

DTMManager.getDTM(int) sometimes returns null for RTF

           Summary: DTMManager.getDTM(int) sometimes returns null for RTF
           Product: XalanJ2
           Version: CurrentCVS
          Platform: All
        OS/Version: Windows NT/2K
            Status: NEW
          Severity: Normal
          Priority: Other
         Component: Xalan
        AssignedTo: xalan-dev@xml.apache.org
        ReportedBy: mkwan@ca.ibm.com


I saw a NullPointerException in the testcase 
extensions\library\libraryNodeset03.xsl when propagating the extension changes 
to Xalan3. The weird thing is that this problem has nothing to do with the 
changes I made. It is also intermittent. I can reproduce it on the command 
line. But the problem disappeared when running inside the debugger. Adding 
another unrelated command line option can also cause the problem to disappear.

I finally traced the problem down to 
org.apache.xpath.objects.XRTreeFrag.finalize(), which calls the destruct() 
method to release the DTM associated with the RTF. The problem is the DTM can 
still be referenced after it is released, causing DTMManager.getDTM(int 
nodeHandle) to return NULL. The finalize() method is called by GC, which 
explains the undeterministic behavior of this bug.

I think the main branch also has this problem although I only saw it in the 
xslt20 branch.