RFR (XS) 6988950: JDWP exit error JVMTI_ERROR_WRONG_PHASE(112)

[serguei.spitsyn at oracle.com]

Please, review the fix for:
   https://bugs.openjdk.java.net/browse/JDK-6988950


Open webrev:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2014/jdk/6988950-JDWP-wrong-phase.1/


Summary:

    The failing scenario:
      The debugger and the debuggee are well aware a VM shutdown has 
been started in the target process.
      The debugger at this point is not expected to send any commands to 
the JDWP agent.
      However, the JDI layer (debugger side) and the jdwp agent 
(debuggee side)
      are not in sync with the consumer layers.

      One reason is because the test debugger does not invoke the JDI 
method VirtualMachine.dispose().
      Another reason is that the Debugger and the debuggee processes are 
uneasy to sync in general.

      As a result the following steps are possible:
        - The test debugger sends a 'quit' command to the test debuggee
        - The debuggee is normally exiting
        - The jdwp backend reports (over the jdwp protocol) an anonymous 
class unload event
        - The JDI InternalEventHandler thread handles the 
ClassUnloadEvent event
        - The InternalEventHandler wants to uncache the matching 
reference type.
          If there is more than one class with the same host class 
signature, it can't distinguish them,
          and so, deletes all references and re-retrieves them again 
(see tracing below):
            MY_TRACE: JDI: 
VirtualMachineImpl.retrieveClassesBySignature: 
sig=Ljava/lang/invoke/LambdaForm$DMH;
        - The jdwp backend debugLoop_run() gets the command from JDI and 
calls the functions
          classesForSignature() and classStatus() recursively.
        - The classStatus() makes a call to the JVMTI GetClassStatus() 
and gets the JVMTI_ERROR_WRONG_PHASE
        - As a result the jdwp backend reports the JVMTI error to the 
JDI, and so, the test fails

      For details, see the analysis in bug report closed as a dup of the 
bug 6988950:
         https://bugs.openjdk.java.net/browse/JDK-8024865

      Some similar cases can be found in the two bug reports (6988950 
and 8024865) describing this issue.

      The fix is to skip reporting the JVMTI_ERROR_WRONG_PHASE error as 
it is normal at the VM shutdown.
      The original jdwp backend implementation had a similar approach 
for the raw monitor functions.
      Threy use the ignore_vm_death() to workaround the 
JVMTI_ERROR_WRONG_PHASE errors.
      For reference, please, see the file: src/share/back/util.c


Testing:
   Run nsk.jdi.testlist, nsk.jdwp.testlist and JTREG com/sun/jdi tests


Thanks,
Serguei