b29
Finally got to reproduce that problem ...
As a reminder, it since since the build b28 that we first experiment it.
It occurs on the call to close() on the GenericConnector.
Here I got it on an X86 box running Solaris 9.
TCK test that failed is api/javax/management/remote/security/optional/index.html#JmxmpMBeanServerForwarderTest
but other security tests may equally allow to reproduce it.
I do run the TCK with RI logging activated and directed to a file.
Full thread dump in Comments.
When the test went into deadlock, it was dealing with :

=-=-= tests.api.share.utils.MBeanServerConnectionUtils$RemoveNotificationListenerMethod =-=-=

RI debug output just before the deadlock is :

Sep 15, 2003 4:39:14 PM SynchroMessageConnectionImpl close
FINER: Closing the underlying connection.
Sep 15, 2003 4:39:14 PM SocketConnection close
FINER: Close the socket connection.
Sep 15, 2003 4:39:14 PM SocketConnection close
FINEST: java.net.SocketException: Socket closed
java.net.SocketException: Socket closed
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:99)
at java.net.SocketOutputStream.write(SocketOutputStream.java:136)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:66)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:124)
at java.io.ObjectOutputStream$BlockDataOutputStream.flush(ObjectOutputStream.java:1585)
at java.io.ObjectOutputStream.flush(ObjectOutputStream.java:639)
at java.io.ObjectOutputStream.close(ObjectOutputStream.java:660)
at com.sun.jmx.remote.socket.SocketConnection.close(SocketConnection.java:245)
at com.sun.jmx.remote.generic.SynchroMessageConnectionImpl.close(SynchroMessageConnectionImpl.java:332)
at javax.management.remote.generic.GenericConnector.close(GenericConnector.java:270)
at javax.management.remote.generic.GenericConnector.close(GenericConnector.java:225)
at tests.api.javax.management.remote.security.mandatory.MBeanServerForwarderTest.runTest(MBeanServerForwarderTest.java:157)
at tests.api.javax.management.remote.security.mandatory.MBeanServerForwarderTest.runTests(MBeanServerForwarderTest.java:82)
at tests.api.javax.management.remote.security.mandatory.MBeanServerForwarderTest.MBeanServerForwarderTest0001(MBeanServerForwarderTest.java:224)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at com.sun.javatest.lib.TestCases.invokeTestCases(TestCases.java:176)
at com.sun.javatest.lib.MultiTest.run(MultiTest.java:115)
at tests.api.javax.management.remote.security.mandatory.MBeanServerForwarderTest.main(MBeanServerForwarderTest.java:238)
Sep 15, 2003 4:39:14 PM SynchroMessageConnectionImpl close
FINER: Clean all threads waiting theire responses.
Sep 15, 2003 4:39:14 PM ClientIntermediary terminate
FINER: Terminated.
Sep 15, 2003 4:39:14 PM ClientCommunicatorAdmin Checker-run
FINER: Finished.