FW: Creating SAXParser from multiple threads. NULL POINTER EXCEPT ION

["Roytman, Alex" <ro...@peacetech.com>]

I am forwarding this message to xalan list because I've read you have been
having some threading problems with Xerces

-----Original Message-----
From: Roytman, Alex [mailto:roytmana@peacetech.com]
Sent: Tuesday, November 21, 2000 1:01 AM
To: 'xerces-j-dev@xml.apache.org'
Subject: Creating SAXParser from multiple threads. NULL POINTER
EXCEPTION


I have been having some problems with Xerces 1.2.1 in multithreaded
environment for a while. 
So I tried a simple test and it seems to me it shows some problems with
creating SAXParser simultaneously in multiple threads. It blows with
NullPointerException:

java.lang.NullPointerException
at
org.apache.xerces.validators.common.XMLValidator.init(XMLValidator.java:1535
)
at
org.apache.xerces.validators.common.XMLValidator.<init>(XMLValidator.java:40
1)
at org.apache.xerces.framework.XMLParser.<init>(XMLParser.java:203)
at org.apache.xerces.parsers.SAXParser.<init>(SAXParser.java:164)
at pti.gao.gwiz.xmap.dtools.Test$SaxThread.run(Test.java:22)

I only create parser with SAXParser parser = new SAXParser();
I do not even parse - just create.
If I span only one thread everything works fine.
if I put SAXParser parser = new SAXParser(); in synchronized block
everything works fine too.
I do not recall seeing anything about not creating SAXParser with new
SAXParser() but in case I missed it my apologies

here is my simple test program

import org.w3c.dom.Document;
import org.apache.xerces.parsers.SAXParser;

public class Test {
  public static final Object syncObj = new Object();

  public static void main(String[] args) {
    for (int i = 0; i < 3; i++) {
      new SaxThread().start();
    }
  }

  public static class SaxThread extends Thread {
     public void run() {
      for (int i = 0; i < 100; i++) {
        try {
          SAXParser parser;
          //synchronized(syncObj) {
            parser = new SAXParser();
          //}

        } catch (Exception ex) {
          ex.printStackTrace();
        }
      }
      System.out.println("\nDONE " + this);
    }
  }
}

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