RFR (M) 8155951: VM crash in nsk/jvmti/RedefineClasses/StressRedefine: assert failed: Corrupted constant pool

[Daniel D. Daugherty]

Finally caught up on this thread.

The change looks great. I don't see any locking issues
with this fix.

Dan


On 5/16/16 3:42 PM, Coleen Phillimore wrote:
>
> Thank you, David!
> Coleen
>
> On 5/16/16 4:59 PM, David Holmes wrote:
>> Looks good!
>>
>> Thanks,
>> David
>>
>> On 17/05/2016 2:28 AM, Coleen Phillimore wrote:
>>>
>>> David, Thank you for looking at this change.
>>>
>>> On 5/15/16 9:51 PM, David Holmes wrote:
>>>> Hi Coleen,
>>>>
>>>> On 13/05/2016 4:14 AM, Coleen Phillimore wrote:
>>>>> 8151066: assert(0 <= i && i < length()) failed: index out of bounds
>>>>> Summary: lock classes for redefinition because constant pool merging
>>>>> isn't thread safe, use method constant pool because constant pool
>>>>> merging doesn't make equivalent cpCaches because of invokedynamic
>>>>>
>>>>> I had to make these changes together.   See bugs for more details.
>>>>>
>>>>> open webrev at http://cr.openjdk.java.net/~coleenp/8155951/webrev
>>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8155951
>>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8151066
>>>>
>>>> In general the locking approach seems okay - as long as all mutating
>>>> actions on the constantpool are being guarded with this locking.
>>>>
>>>> But I'm concerned that you are using a bit in _misc_flags for this
>>>> mutable state. It isn't clear to me when the other bits in _misc_flags
>>>> might be set but I'm assuming only during initial class parsing, or
>>>> some other single-threaded use? Putting a mutable bit into such a flag
>>>> set is fragile and can only be done once.
>>>
>>> I was uneasy about this too.  Most of the _misc_flags are set during
>>> initialization but there are a couple that are set while the vm is
>>> running.   I moved _is_being_redefined to a bool sized gap just about
>>> the _misc_flags, which makes me more confident of the state of this
>>> field when doing locking.
>>>
>>> Retesting this small change with StressRedefine in a loop.
>>>
>>> open webrev at http://cr.openjdk.java.net/~coleenp/8155951.02/webrev
>>>
>>> Thanks,
>>> Coleen
>>>
>>>>
>>>> Thanks,
>>>> David
>>>>
>>>>
>>>>> Tested with rbt nightly test and 24 hours with StressRedefine test.
>>>>>
>>>>> Thanks,
>>>>> Coleen
>>>>>
>>>>>
>>>>>
>>>
>
>