[AXIS-2518] Problem overriding ThreadLocal's initialValue method in ThreadLocalDocumentBuilder

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.4
• Component/s: Basic Architecture
• Environment: Windows XP, jdk 1.4.1_7 build 1.4.2_07-b05, mixed mode
• Assignee: Unassigned
• Reporter: Rajkumar Kothapa
• Created: 06/Jul/06 21:27
• Updated: 06/Jul/06 21:27

Description

I am using Axis 1.4 and jvm version "build 1.4.2_07-b05, mixed mode" and i
am getting the following exception under heavy loads.

java.lang.NullPointerException
at
java.lang.ThreadLocal$ThreadLocalMap$Entry.access$502(ThreadLocal.java:229)
at
java.lang.ThreadLocal$ThreadLocalMap.replaceStaleEntry(ThreadLocal.java:509)
at java.lang.ThreadLocal$ThreadLocalMap.getAfterMiss(ThreadLocal.java:362)
at java.lang.ThreadLocal$ThreadLocalMap.get(ThreadLocal.java:341)
at java.lang.ThreadLocal$ThreadLocalMap.access$000(ThreadLocal.java:219)
at java.lang.ThreadLocal.get(ThreadLocal.java:121)
at org.apache.axis.utils.XMLUtils.getDocumentBuilder(XMLUtils.java:237)
at org.apache.axis.utils.XMLUtils.newDocument(XMLUtils.java:337)
at
org.apache.axis.message.SOAPDocumentImpl.<init>(SOAPDocumentImpl.java:70)
at org.apache.axis.SOAPPart.<init>(SOAPPart.java:1020)
at org.apache.axis.Message.setup(Message.java:377)
at org.apache.axis.Message.<init>(Message.java:235)
at org.apache.axis.transport.http.AxisServlet.doPost(AxisServlet.java:628)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
at
org.apache.axis.transport.http.AxisServletBase.service(AxisServletBase.java:327)

We are facing this issue because:
XMLUtils.getDocumentBuilder calls ThreadLocal.get
ThreadLocal.get calls ThreadLocalDocumentBuilder.initialValue
ThreadLocalDocumentBuilder.initialValue calls
DocumentBuilderFactory.newInstance()
While creating an instance of DocumentBuilderFactory the classLoader is
creating a ThreadLocal.

This re-entrant call to the ThreadLocalMap results in the NPE. This is a
known issue according to Sun which has been fixed in Java SE 6.
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5025230. We had a
discussion regarding this on the JSR 166 concurrency list
(http://altair.cs.oswego.edu/mailman/private/concurrency-interest/2006-June/002789.html)
and the only work-around for this to work on JDK 1.4 and JDK 5 is NOT to
override ThreadLocal.initialValue.

The current code is:

private static class ThreadLocalDocumentBuilder extends ThreadLocal {
protected Object initialValue() {
try

{ return getDOMFactory().newDocumentBuilder(); }

catch (ParserConfigurationException e)

{ log.error(Messages.getMessage("parserConfigurationException00"), e); }

return null;
}
}

Recommended code:
private static class ThreadLocalDocumentBuilder extends ThreadLocal {
public Object get() {
Object result = super.get();
if(result == null){
try

{ result = getDOMFactory().newDocumentBuilder(); set(result); }

catch (ParserConfigurationException e)

{ log.error(Messages.getMessage("parserConfigurationException00"), e); }

}

return result;
}
}

Would it be possible to checkin this change?