[ http://issues.apache.org/jira/browse/XALANJ-1198?page=history ]
Brian Minchau resolved XALANJ-1198:
-----------------------------------
Assign To: (was: Xalan Developers Mailing List)
Resolution: Won't Fix
Xalan's DOMSource is not thread safe. But as noted by Joe K. DOMs are not
promised to be threadsafe. So I'm resolving this one as "Won't Fix". Re-open
this one if you feel strongly about this one, which would be an enhancement
rather than a bug.
> Xalan's DOMSource is not thread-safe
> ------------------------------------
>
> Key: XALANJ-1198
> URL: http://issues.apache.org/jira/browse/XALANJ-1198
> Project: XalanJ2
> Type: Bug
> Components: JAXP
> Versions: 2.3Dx
> Environment: Operating System: Windows NT/2K
> Platform: PC
> Reporter: Vlad Mamut
> Priority: Critical
>
> When using Xalan in a multi-threaded environment and DOMSource is used for
> transformations, occasional java.lang.NullPointerException are thrown.
> A program running multiple printing threads accesses the same DOM document.
> The
> printing uses transformation to serialize the document content into an output
> stream. An exception is thrown when Transformer.transform() is called.
> Replacing
> DOMSource with StreamSource seems to alleviate the problem.
> Attached are the test results and the source used to reproduce the problem.
> Similar results (NullPointerExceptions in
> org.apache.xml.utils.TreeWalker.dispatachChars) are produced when using
> Serializer in multi-threaded environment. It might be a separate issue
> deserving
> it 'own' bug.
> Case 1 (exception in 2 threads)
> *******************************
> C:\CitiFile\PrintException>java TestSerializer
> C:\Citifile\PrintException\data.x
> ml
> Classpath: .;xalan.jar;xml-apis.jar
> Starting processing Thread ID: 0
> Enter Print Thread ID: 0
> Starting processing Thread ID: 1
> Enter Print Thread ID: 1
> Starting processing Thread ID: 2
> Enter Print Thread ID: 2
> Exception in Thread ID: 1
> java.lang.NullPointerException
> at org.apache.xml.utils.TreeWalker.dispatachChars(TreeWalker.java:275)
> at org.apache.xml.utils.TreeWalker.startNode(TreeWalker.java:419)
> at org.apache.xml.utils.TreeWalker.traverse(TreeWalker.java:183)
> at
> org.apache.xalan.transformer.TransformerIdentityImpl.transform(Transf
> ormerIdentityImpl.java:325)
> at SerializerThread.printXMLdocument(SerializerThread.java:46)
> at SerializerThread.run(SerializerThread.java:26)
> Exception in Thread ID: 0
> java.lang.NullPointerException
> at org.apache.xml.utils.TreeWalker.dispatachChars(TreeWalker.java:275)
> at org.apache.xml.utils.TreeWalker.startNode(TreeWalker.java:419)
> at org.apache.xml.utils.TreeWalker.traverse(TreeWalker.java:183)
> at
> org.apache.xalan.transformer.TransformerIdentityImpl.transform(Transf
> ormerIdentityImpl.java:325)
> at SerializerThread.printXMLdocument(SerializerThread.java:46)
> at SerializerThread.run(SerializerThread.java:26)
> Exit Print Thread ID: 2
> Completed Thread ID: 2
> Case 2 (exception in 1 thread)
> ******************************
> C:\CitiFile\PrintException>java TestSerializer
> C:\Citifile\PrintException\data.x
> ml
> Classpath: .;xalan.jar;xml-apis.jar
> Starting processing Thread ID: 0
> Enter Print Thread ID: 0
> Starting processing Thread ID: 1
> Enter Print Thread ID: 1
> Starting processing Thread ID: 2
> Enter Print Thread ID: 2
> Exception in Thread ID: 1
> java.lang.NullPointerException
> at org.apache.xml.utils.TreeWalker.dispatachChars(TreeWalker.java:275)
> at org.apache.xml.utils.TreeWalker.startNode(TreeWalker.java:419)
> at org.apache.xml.utils.TreeWalker.traverse(TreeWalker.java:183)
> at
> org.apache.xalan.transformer.TransformerIdentityImpl.transform(Transf
> ormerIdentityImpl.java:325)
> at SerializerThread.printXMLdocument(SerializerThread.java:46)
> at SerializerThread.run(SerializerThread.java:26)
> Exit Print Thread ID: 0
> Completed Thread ID: 0
> Exit Print Thread ID: 2
> Completed Thread ID: 2
> Case 3 (no exceptions, successful processing)
> *********************************************
> C:\CitiFile\PrintException>java TestSerializer
> C:\Citifile\PrintException\data.x
> ml
> Classpath: .;xalan.jar;xml-apis.jar
> Starting processing Thread ID: 0
> Enter Print Thread ID: 0
> Starting processing Thread ID: 1
> Enter Print Thread ID: 1
> Starting processing Thread ID: 2
> Enter Print Thread ID: 2
> Exit Print Thread ID: 0
> Completed Thread ID: 0
> Exit Print Thread ID: 1
> Completed Thread ID: 1
> Exit Print Thread ID: 2
> Completed Thread ID: 2
> *****************************************************************************
> import org.w3c.dom.Document;
> import javax.xml.parsers.DocumentBuilder;
> import javax.xml.parsers.DocumentBuilderFactory;
> import java.io.FileInputStream;
> public class TestSerializer {
> public static void main (String[] args) {
> try {
> System.out.println("Classpath: " +
> System.getProperty("java.class.path"));
> DocumentBuilderFactory dbFactory =
> DocumentBuilderFactory.newInstance();
> DocumentBuilder dBuilder =
> dbFactory.newDocumentBuilder();
> Document xmlDocument = dBuilder.parse(new
> FileInputStream("data.xml"));
> for (int i=0; i < 3; i++) {
> new SerializerThread(xmlDocument, i).start();
> }
> }
> catch (Exception ex) {
> ex.printStackTrace();
> }
> }
> }
> *****************************************************************************
> import org.w3c.dom.Document;
> import javax.xml.transform.dom.DOMSource;
> import javax.xml.transform.stream.StreamSource;
> import javax.xml.transform.stream.StreamResult;
> import javax.xml.transform.TransformerFactory;
> import javax.xml.transform.Transformer;
> import java.io.FileInputStream;
> import java.io.FileOutputStream;
> public class SerializerThread extends Thread {
> private Document xmlDocument;
> private int threadId;
> public SerializerThread(Document xmlDocument, int threadId) {
> this.xmlDocument = xmlDocument;
> this.threadId = threadId;
> }
> public void run() {
> try {
> System.out.println("Starting processing Thread ID: " +
> this.threadId);
> printXMLdocument(this.xmlDocument);
> System.out.println("Completed Thread ID: " + this.threadId);
> }
> catch (Exception ex) {
> System.out.println("Exception in Thread ID: " + this.threadId);
> ex.printStackTrace();
> }
> }
> private void printXMLdocument(Document xmlDocument) throws Exception {
> System.out.println("Enter Print Thread ID: " + this.threadId);
> StreamResult result = new StreamResult(new FileOutputStream("out" +
> this.threadId + ".xml"));
> /*** replacing DOMSource with StreamSource works *******/
> DOMSource source = new DOMSource(xmlDocument);
> // StreamSource source = new StreamSource(new
> FileInputStream("data.xml"));
> /*******************************************************/
> TransformerFactory transformerFactory =
> TransformerFactory.newInstance();
> Transformer transformer = transformerFactory.newTransformer();
> transformer.transform(source, result);
> System.out.println("Exit Print Thread ID: " + this.threadId);
> }
> }
> *****************************************************************************
> I use:
> Sun JVM (java version "1.3.1_02", Java(TM) 2 Runtime Environment, Standard
> Edition (build 1.3.1_02-b02), Java HotSpot(TM) Client VM (build 1.3.1_02-b02,
> mixed mode))
> Xalan J 2.3.1
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