Details
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Bug
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Status: Closed
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Major
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Resolution: Fixed
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3.4.4
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None
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Unknown
Description
I have a multithreaded application where each thread does the following:
new SomeService
.getPort()
.invokeSomeEndpointMethod()
The first invocation of the endpoint method cases the following error:
java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.neethi.builders.converters.ConverterRegistry.findQName(ConverterRegistry.java:121) at org.apache.neethi.PolicyBuilder.processOperationElement(PolicyBuilder.java:204) at org.apache.neethi.PolicyBuilder.getPolicyOperator(PolicyBuilder.java:174) at org.apache.neethi.PolicyBuilder.getPolicy(PolicyBuilder.java:124) at org.apache.cxf.ws.policy.attachment.wsdl11.Wsdl11AttachmentPolicyProvider.getElementPolicy(Wsdl11AttachmentPolicyProvider.java:192) at org.apache.cxf.ws.policy.attachment.wsdl11.Wsdl11AttachmentPolicyProvider.getElementPolicy(Wsdl11AttachmentPolicyProvider.java:168) at org.apache.cxf.ws.policy.attachment.wsdl11.Wsdl11AttachmentPolicyProvider.getElementPolicy(Wsdl11AttachmentPolicyProvider.java:161) at org.apache.cxf.ws.policy.attachment.wsdl11.Wsdl11AttachmentPolicyProvider.getEffectivePolicy(Wsdl11AttachmentPolicyProvider.java:75) at org.apache.cxf.ws.policy.PolicyEngineImpl.getAggregatedServicePolicy(PolicyEngineImpl.java:461) at org.apache.cxf.ws.policy.EndpointPolicyImpl.initializePolicy(EndpointPolicyImpl.java:151) at org.apache.cxf.ws.policy.EndpointPolicyImpl.initialize(EndpointPolicyImpl.java:140) at org.apache.cxf.ws.policy.PolicyEngineImpl.createEndpointPolicyInfo(PolicyEngineImpl.java:614) at org.apache.cxf.ws.policy.PolicyEngineImpl.getEndpointPolicy(PolicyEngineImpl.java:326) at org.apache.cxf.ws.policy.PolicyEngineImpl.getClientEndpointPolicy(PolicyEngineImpl.java:313) at org.apache.cxf.ws.policy.PolicyDataEngineImpl.getClientEndpointPolicy(PolicyDataEngineImpl.java:61) at org.apache.cxf.transport.http.HTTPConduit.updateClientPolicy(HTTPConduit.java:326) at org.apache.cxf.transport.http.HTTPConduit.updateClientPolicy(HTTPConduit.java:346) at org.apache.cxf.transport.http.HTTPConduit.getClient(HTTPConduit.java:892) at org.apache.cxf.transport.http.HTTPConduit.configureConduitFromEndpointInfo(HTTPConduit.java:368) at org.apache.cxf.transport.http.HTTPConduit.finalizeConfig(HTTPConduit.java:448) at org.apache.cxf.transport.http.HTTPTransportFactory.getConduit(HTTPTransportFactory.java:249) at org.apache.cxf.binding.soap.SoapTransportFactory.getConduit(SoapTransportFactory.java:226) at org.apache.cxf.binding.soap.SoapTransportFactory.getConduit(SoapTransportFactory.java:233) at org.apache.cxf.endpoint.AbstractConduitSelector.createConduit(AbstractConduitSelector.java:144) at org.apache.cxf.endpoint.AbstractConduitSelector.getSelectedConduit(AbstractConduitSelector.java:108) at org.apache.cxf.endpoint.UpfrontConduitSelector.prepare(UpfrontConduitSelector.java:63) at org.apache.cxf.endpoint.ClientImpl.prepareConduitSelector(ClientImpl.java:887) at org.apache.cxf.endpoint.ClientImpl.doInvoke(ClientImpl.java:525) at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:441) at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:356) at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:314) at org.apache.cxf.frontend.ClientProxy.invokeSync(ClientProxy.java:96) at org.apache.cxf.jaxws.JaxWsClientProxy.invoke(JaxWsClientProxy.java:140) ... at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:573) Caused by: java.lang.NullPointerException at com.sun.org.apache.xerces.internal.dom.DeferredElementNSImpl.synchronizeData(DeferredElementNSImpl.java:108) at com.sun.org.apache.xerces.internal.dom.ElementNSImpl.getLocalName(ElementNSImpl.java:338) at org.apache.neethi.builders.converters.AbstractDOMConverter.getQName(AbstractDOMConverter.java:43) ... 45 more
From there on, everything works fine. The service in question uses policies, and apparently policies are lazily initialized.
The actual failure is triggered by a race condition causing ElementNSImpl from xerces to be being shared across threads as a consequence.
This happens in org.apache.cxf.ws.policy.attachment.wsdl11.Wsdl11AttachmentPolicyProvider.getElementPolicy, when the PolicyRegistry is consulted:
Policy policy = registry.lookup(id);
if (policy == null) {
try {
policy = builder.getPolicy(e.getElement());
All threads will start building the missing policy, as there is nothing in the registry and no synchronization on a cache miss. Some thread wins the race and gets a usable result from e.getElement() and stores the result in the registry, the others hit the NPE-error.
I do not really understand all the internal workings, but I can cure this problem by changing the code snippet to:
synchronized (e.getElement()) {
Policy policy = registry.lookup(id);
if (policy == null) {
try {
policy = builder.getPolicy(e.getElement());
...
}
That solves the race to initialize the entry in the registry, but not the real problem.
This leaves me with 3 questions:
Is there a way to eagerly populate the PolicyRegistry as an user of CXF?
Shouldn't Wsdl11AttachmentPolicyProvider be thread safe, if policies are to be lazily initialized?
How do we prevent the WSDLManager in the Service from sharing non-tread safe items (ElementNSImpl) across threads?
Apparently org.apache.cxf.jaxws.ServiceImpl.initialize always selects the same bus, which cases the WSDLManager to be shared between threads. Normally that would be a good thing, since we can share the WSDL-cache.
I tried to build a test-case, so far I have no luck in building the required configuration. Also, which submodule is to blame here? A lot of components are involved.
Please ask for more details if required.
Thanks,
Kim Johan Andersson
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