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

[Dmitry Samersoff]

Serguei,

Thank you!

Fix looks good for me.

-Dmitry

On 2014-10-29 17:35, serguei.spitsyn at oracle.com wrote:
> Dmitry,
> 
> Yes, it will return NULL if the case of JVMTI_ERROR_WRONG_PHASE error.
> It is Ok for the getMethodClass() as the NULL return value listed in the
> comment.
> It seems to be Ok for other two uses of the methodClass().
> 
> Thanks!
> Serguei
> 
> On 10/29/14 6:59 AM, Dmitry Samersoff wrote:
>> Serguei,
>>
>> What happens in a caller function if we ignore the error?
>>
>> e. g. getMethodClass has the code:
>> ...
>>
>>      error = methodClass(method, &clazz);
>>      if ( error != JVMTI_ERROR_NONE ) {
>>          EXIT_ERROR(error,"Can't get jclass for a methodID, invalid?");
>>          return NULL;
>>      }
>>      return clazz;
>>
>> after the fix it probably will return NULL. Is it correct?
>>
>> -Dmitry
>>
>> On 2014-10-29 04:11, serguei.spitsyn at oracle.com wrote:
>>> 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
>>>
>>
> 


-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the sources.