Multiple threads: getPort Hangs on 100% CPU with fast infoset on asynchronous invocation

Hi,
i'm caching an instance of javax.xml.ws.Service.
I cache the results of getPort in a ThreadLocal.
When i use multiple parallel asynchronous invocations, this approach does not seem to work, so i invoke getPort for each asynchronous invocation.
I have 8 threads using a web service running in parallel on a i7.
After about 20h of work, all my worker threads are hanging on:

"pool-41-thread-7" prio=10 tid=0x00007f8cc469d400 nid=0x156a runnable [0x000000004691a000..0x0000000046921ba0]
java.lang.Thread.State: RUNNABLE
at java.util.HashMap.put(HashMap.java:374)
at java.util.HashSet.add(HashSet.java:200)
at org.jboss.ws.metadata.umdm.FeatureSet.addFeature(FeatureSet.java:63)
at org.jboss.ws.metadata.umdm.EndpointMetaData.addFeature(EndpointMetaData.java:375)
at org.jboss.ws.core.jaxws.client.ClientFeatureProcessor.processFeature(ClientFeatureProcessor.java:84)
at org.jboss.ws.core.jaxws.spi.ServiceDelegateImpl.initWebserviceFeatures(ServiceDelegateImpl.java:537)
at org.jboss.ws.core.jaxws.spi.ServiceDelegateImpl.getPort(ServiceDelegateImpl.java:526)
at javax.xml.ws.Service.getPort(Service.java:607)
at com.spratpix.subdomains.ThreadLocalWebserviceProxy.getAsyncPort(ThreadLocalWebserviceProxy.java:47)

Here is how i use getPort

protected T getAsyncPort() {
long t0 = System.nanoTime();
try

{ return service.getPort(portClass, new FastInfosetFeature()); }

finally

{ long dt = System.nanoTime() - t0; TimingInterceptor.callChain.addInvocationWithMethod(method, dt); }

}

And the problematic web service call seems to be

public Future<Boolean> PutFileAsync(String domain, String type, String filename, S3Object file, AsyncHandler<Boolean> asyncHandler);