Description of problem:

EAP 6.1.0.ER2, 6.1.0.ER3

Test org.jgroups.tests.UnicastLoopbackTest.testUnicastMsgsWithLoopback fails randomly with following error message:
Test timed out before all messages were received

java.lang.AssertionError 
at org.testng.Assert.fail(Assert.java:94) 
at org.jgroups.tests.UnicastLoopbackTest.testUnicastMsgsWithLoopback(UnicastLoopbackTest.java:78) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:88) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55) 
at java.lang.reflect.Method.invoke(Method.java:613) 
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:80) 
at org.testng.internal.InvokeMethodRunnable.runOne(InvokeMethodRunnable.java:46) 
at org.testng.internal.InvokeMethodRunnable.run(InvokeMethodRunnable.java:37) 
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:482) 
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:345) 
at java.util.concurrent.FutureTask.run(FutureTask.java:177) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1156) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:626) 
at java.lang.Thread.run(Thread.java:780) 

This is not due to slow machines though, the timeouts are quite generous and when the test passes, it is done quickly (~4 seconds, timeout is set to 20 seconds). Also note that this is specific for tcp variation.

https://jenkins.mw.lab.eng.bos.redhat.com/hudson/view/EAP6/view/EAP6-JGroups/job/eap-6x-jgroups-rhel-matrix/27/jdk=ibm17,label=RHEL5_x86_64/testReport/org.jgroups.tests/UnicastLoopbackTest/testUnicastMsgsWithLoopback/