[AXIS2-1570] Rampart/Axiom is not thread safe

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.0
• Component/s: modules
• Environment: WinXP, Tomcat 4/5, Websphere 5/6
• Assignee: Ruchith B. Gunaratne
• Reporter: Johan Andersson
• Created: 01/Nov/06 08:32
• Updated: 11/Dec/08 22:28
• Resolved: 19/Nov/06 05:34

Description

The Axiom DOM (distributed with Axis 1.0) implementation seems to have some threading issues.

The problem manifests itself as a nullpointer exception in org.apache.axiom.om.impl.dom.jaxp.DocumentBuilderFactoryImpl

If I apply a moderate amount of load on the server so the number of http processor threads start increase the NPE will
happen all of the time whenever a piece of code tries to create a DocumentBuilder (for instance the WSDL parsing during deployment).
I can reproduce this problem quite reliably.

Nullpointer is caused by the originalDocumentBuilderFactory being null
— snip —
public DocumentBuilder newDocumentBuilder()
throws ParserConfigurationException

{ /** * Determine which DocumentBuilder implementation should be returned */ return isDOOMRequired() ? new DocumentBuilderImpl() : originalDocumentBuilderFactory.newDocumentBuilder(); }

— snip —

I've tracked the problem to this piece of code in the org.apache.axiom.om.impl.dom.jaxp.DocumentBuilderFactoryImpl

— snip —
public static void setDOOMRequired(boolean isDOOMRequired) {
String systemKey = DocumentBuilderFactory.class.getName();
if (isDOOMRequired) {
if (!isDOOMRequired())

{ originalDocumentBuilderFactory = DocumentBuilderFactory.newInstance(); originalDocumentBuilderFactoryClassName = originalDocumentBuilderFactory.getClass().getName(); documentBuilderFactoryTracker.set(Boolean.TRUE); System.setProperty(systemKey, DocumentBuilderFactoryImpl.class.getName()); }

} else {
String currentFactoryClassName = DocumentBuilderFactory.newInstance().getClass().getName();
if (currentFactoryClassName != null && currentFactoryClassName.equals(DocumentBuilderFactoryImpl.class.getName())) {
System.getProperties().remove(systemKey);
if (originalDocumentBuilderFactoryClassName != null)

{ System.setProperty(DocumentBuilderFactory.class.getName(), originalDocumentBuilderFactoryClassName); }

}
documentBuilderFactoryTracker.set(null);
originalDocumentBuilderFactory = null;
}
}
— snip —

Trying to find away to resolve this I realise that the DOOM document builder factory implementation is in fact manipulating a JVM-wide
system property in a multi-threaded environment which besides the problem I am currently experiencing could lead to all sorts
of unwanted side-effects.

As I don't want to allow this to happen I simply commented out the contents of the setDoomRequired() method hoping that Rampart could work
with my default DOM instead and that I would only suffer some performance loss.

I was wrong in that assumption as I encountered another problem:

StAXOMBuilder CHARACTERS: [org.apache.axis2.AxisFault: WSDoAllReceiver: security processing failed; nested exception is:
org.apache.ws.security.WSSecurityException: Cannot encrypt/decrypt data; nested exception is:
org.w3c.dom.DOMException: HIERARCHY_REQUEST_ERR: An attempt was made to insert a node where it is not permitted.
at org.apache.axis2.security.WSDoAllReceiver.processMessage(WSDoAllReceiver.java:183)
at org.apache.axis2.security.handler.WSDoAllHandler.invoke(WSDoAllHandler.java:82)
at org.apache.axis2.engine.Phase.invoke(Phase.java:381)
at org.apache.axis2.engine.AxisEngine.invoke(AxisEngine.java:473)
at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:445)
at org.apache.axis2.transport.http.HTTPTransportUtils.processHTTPPostRequest(HTTPTransportUtils.java:284)
at org.apache.axis2.transport.http.AxisServlet.doPost(AxisServlet.java:157)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:716)

I compared the source of org.apache.axiom.om.impl.dom.jaxp.DocumentBuilderFactoryImpl in Axis 1.0 release and the latest in SVN
http://svn.apache.org/viewvc/webservices/commons/trunk/modules/axiom/modules/axiom-dom/src/main/java/org/apache/axiom/om/impl/dom/jaxp/DocumentBuilderFactoryImpl.java?view=markup
and can see no changes in how this is handled.

Issue Links

• is blocked by: AXIOM-69 org.apache.axiom.om.impl.dom.DocumentImpl#importNode() does not work properly
• is duplicated by: AXIOM-3 NullPointerException in DocumentBuilderFactoryImpl