[ http://issues.apache.org/jira/browse/XALANJ-1198?page=comments#action_59753 ] Brian Minchau commented on XALANJ-1198: ---------------------------------------
Jae Shin has made a comment on this issue recently, but in bugzilla, where he has seen this problem in a single threaded situation and the text node has zero characters. I hope he will supply more information (like a simple test case!). The enhancement request by Vlad from 2002-09-26, to have some an option to make a DOM thread safe or not is no small task. Of course a thread safe DOM would be slower. However, I think that the DOM in question is produced by an XML parser, not the XSLT processor (Xalan). So this is outside of Xalan's domain. The last update to this issue was over two years ago, and looks like a user error, so unless Jae, or someone else provides a testcase where a single threaded transformation shows a NullPointerException, we will be closing this one down. > 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 > Assignee: Xalan Developers Mailing List > 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 -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - If you want more information on JIRA, or have a bug to report see: http://www.atlassian.com/software/jira --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
