RFR (XS) 6471769: Error: assert(_cur_stack_depth == count_frames(), "cur_stack_depth out of sync")

[serguei.spitsyn at oracle.com]

Thanks, Dmitry!
Serguei

On 2/1/14 1:02 AM, Dmitry Samersoff wrote:
> Looks good for me!
>
> On 2014-02-01 06:58, serguei.spitsyn at oracle.com wrote:
>> Please, review the fix for:
>>    https://bugs.openjdk.java.net/browse/JDK-6471769
>>
>>
>> Open webrev:
>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2014/hotspot/6471769-JVMTI-FRAME/
>>
>>
>> Summary:
>>
>>    There is a general issue in the suspend equivalent condition mechanism:
>>    Two subsequent calls to the JvmtiEnv::is_thread_fully_suspended() may
>> return different results:
>>      - 1-st: true
>>      - 2-nd: false
>>
>>    This more generic suspend equivalent issue is covered by another bug:
>>      https://bugs.openjdk.java.net/browse/JDK-6280037
>>
>>    The bug to fix in this review is a specific manifestation of the 6280037
>>    in the JVMTI GetFrameCount() that has a big impact on the SQE nightly.
>>    It is on the Test Stabilization radar (as well as the 6280037).
>>    There are many tests intermittently failing because of this.
>>
>>    The webrev for review is a one-liner work around the 6280037 for the
>> GetFrameCount().
>>
>>    The JVMTI GetFrameCount() spec tells:
>>      "If this function is called for a thread actively executing
>> bytecodes (for example,
>>       not the current thread and not suspended), the information returned
>> is transient."
>>
>>    So, it is Ok to call the GetFrameCount() for non-suspended target
>> threads.
>>    To achieve safety, the frame count for non-suspended threads is
>> calculated at a safepoint.
>>    It should be Ok and more safe to do the same for suspended threads as
>> well.
>>    There is no big performance impact because it is already on a slow path.
>>    It is still important to avoid safepointing when the target thread is
>> current.
>>
>>    The bug 6280037 should go out of the Test Stabilization radar (remove
>> the svc-nightly label)
>>    as the most of the impacted tests are covered by the 6471769.
>>
>>
>> Testing:
>>    In progress: nsk.jvmti, nsk.jdi, nsk.jdwp, impacted JTreg tests
>>
>>
>> Thanks,
>> Serguei
>>
>