Here is an entry from my nightly analysis report:

New JDI_REGRESSION failures (from 2007.08.16)
    com/sun/jdi/InvokeHangTest.java
        This test failed due to "failure: Debuggee appears to be hung"
        on Solaris SPARC Client VM (machine vm-b1600s-4) and Solaris
        SPARC Server VM (machine vm-b1600s-3). This test is covered by
        the following bug:

            6280037 4/4 jtreg StepTest is failed intermittently with
                        assert: thread is not fully suspended

        However, this failure mode is different.

        Last failure on 2007.12.15 with Solaris SPARC Client VM (machine capricornus)
        Previous failure on 2007.12.12 with Solaris SPARC Server VM (machine vm-b1600s-1)

The above entry was with Dolphin-B18 JDK bits, but with a newer VM
so this is a Dolphin-B19ish failure.

Below is a .jtr snippet from a failing run on 2007.12.15:

  Debugger: Breakpoint hit at InvokeHangTarg:94
  Debugger: Invoking in threadinstance of InvokeHangTarg(name='Thread 1', id=65)
  Debugger: Invoke done
  Debugger: Breakpoint hit at InvokeHangTarg:110
  Debugger: Invoking in threadinstance of InvokeHangTarg(name='Thread 2', id=70)
failure: Debuggee appears to be hung
java.lang.Exception: InvokeHangTest: failed; bkpts = 64
at InvokeHangTest.runTests(InvokeHangTest.java:275)
at TestScaffold.startTests(TestScaffold.java:429)
at InvokeHangTest.main(InvokeHangTest.java:142)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:623)
at com.sun.javatest.regtest.MainWrapper$MainThread.run(MainWrapper.java:78)
at java.lang.Thread.run(Thread.java:674)

JavaTest Message: Test threw exception: java.lang.Exception: InvokeHangTest: failed; bkpts = 64
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.laILW = testbug leading to failures noise; Xcomp running 1 test; none = LLH = P5ng.Exception: InvokeHangTest: failed; bkpts = 64
IOException reading output of child java interpreter:Stream closed
com.sun.jdi.VMDisconnectedException
at com.sun.tools.jdi.TargetVM.waitForReply(TargetVM.java:304)
at com.sun.tools.jdi.VirtualMachineImpl.waitForTargetReply(VirtualMachineImpl.java:1035)
at com.sun.tools.jdi.PacketStream.waitForReply(PacketStream.java:69)
at com.sun.tools.jdi.JDWP$ObjectReference$InvokeMethod.waitForReply(JDWP.java:4589)
at com.sun.tools.jdi.ObjectReferenceImpl.invokeMethod(ObjectReferenceImpl.java:392)
at InvokeHangTest.doInvoke(InvokeHangTest.java:150)
at InvokeHangTest.breakpointReached(InvokeHangTest.java:196)
at TestScaffold$EventHandler.notifyEvent(TestScaffold.java:191)
at TestScaffold$EventHandler.run(TestScaffold.java:275)
at java.lang.Thread.run(Thread.java:674)
failure: Exception
FAILED: Exception occured in eventHandler: com.sun.jdi.VMDisconnectedException: connection is closed
com.sun.jdi.VMDisconnectedException: connection is closed
at com.sun.tools.jdi.TargetVM.send(TargetVM.java:293)
at com.sun.tools.jdi.VirtualMachineImpl.sendToTarget(VirtualMachineImpl.java:1031)
at com.sun.tools.jdi.PacketStream.send(PacketStream.java:59)
at com.sun.tools.jdi.JDWP$EventRequest$Set.enqueueCommand(JDWP.java:6765)
at com.sun.tools.jdi.JDWP$EventRequest$Set.process(JDWP.java:6735)
at com.sun.tools.jdi.EventRequestManagerImpl$EventRequestImpl.set(EventRequestManagerImpl.java:202)
at com.sun.tools.jdi.EventRequestManagerImpl$EventRequestImpl.setEnabled(EventRequestManagerImpl.java:166)
at com.sun.tools.jdi.EventRequestManagerImpl$EventRequestImpl.enable(EventRequestManagerImpl.java:151)
at InvokeHangTest.breakpointReached(InvokeHangTest.java:201)
at TestScaffold$EventHandler.notifyEvent(TestScaffold.java:191)
at TestScaffold$EventHandler.run(TestScaffold.java:275)
at java.lang.Thread.run(Thread.java:674)
result: Failed. Execution failed: `main' threw exception: java.lang.Exception: InvokeHangTest: failed; bkpts = 64


test result: Failed. Execution failed: `main' threw exception: java.lang.Exception: InvokeHangTest: failed; bkpts = 64