(XS) RFR: 8152849: share/vm/runtime/mutex.cpp:1161 assert(((uintptr_t(_owner))|(uintptr_t(_LockWord.FullWord))|(uintptr_t(_EntryList))|(uintptr_t(_WaitSet))|(uintptr_t(_OnDeck))) == 0) failed

[David Holmes]

Thanks Jerry - afraid I already pushed however :)

David

On 19/08/2016 12:13 PM, Gerald Thornbrugh wrote:
> Hi David,
>
> Your changes looks good.
>
> Jerry
>> Thanks Dan!
>>
>> Still need a second reviewer please. It's really simple :)
>>
>> David
>>
>> On 19/08/2016 12:04 AM, Daniel D. Daugherty wrote:
>>> On 8/17/16 6:04 PM, David Holmes wrote:
>>>> Hi Dan,
>>>>
>>>> Thanks for looking at this.
>>>
>>> No problem. I'm pretty sure I once chased the older version
>>> of this bug... :-)
>>>
>>>
>>>>
>>>> On 17/08/2016 10:59 PM, Daniel D. Daugherty wrote:
>>>>> On 8/17/16 1:45 AM, David Holmes wrote:
>>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8152849
>>>>>>
>>>>>> webrev: http://cr.openjdk.java.net/~dholmes/8152849/webrev/
>>>>>
>>>>> src/share/vm/runtime/mutex.cpp
>>>>>     If the problem is a racy clearing of one of the fields, then the
>>>>>     assert can still fire and the extra info might still show zeroes
>>>>>     since they are two different queries of the fields.
>>>>>
>>>>>     For this diagnostic to be always accurate you need to save a copy
>>>>>     of each field, assert() that all the copies or'ed together are
>>>>> == 0,
>>>>>     and have the extra info printed from the copies.
>>>>
>>>> You are right of course. Don't know what I was thinking. :(
>>>>
>>>> http://cr.openjdk.java.net/~dholmes/8152849/webrev.v2/
>>>
>>> src/share/vm/runtime/mutex.cpp
>>>     No comments.
>>>
>>> Thumbs up!
>>>
>>> Dan
>>>
>>>
>>>
>>>>
>>>> Thanks,
>>>> David
>>>>
>>>>> Dan
>>>>>
>>>>>
>>>>>>
>>>>>> This is a rare assertion failure that has proven to unreproducible
>>>>>> even by directly trying to exercise the theoretical race conditions
>>>>>> mentioned in the bug report. All I can do for now is augment the
>>>>>> assert to print out the various values so we can at least see where
>>>>>> things are failing, next time it happens.
>>>>>>
>>>>>> Example output:
>>>>>>
>>>>>> #  Internal Error
>>>>>> (/scratch/dh198349/jdk9-hs/hotspot/src/share/vm/runtime/mutex.cpp:1157),
>>>>>>
>>>>>>
>>>>>> pid=21732, tid=21734
>>>>>> #
>>>>>> assert(((uintptr_t(_owner))|(uintptr_t(_LockWord.FullWord))|(uintptr_t(_EntryList))|(uintptr_t(_WaitSet))|(uintptr_t(_OnDeck)))
>>>>>>
>>>>>>
>>>>>> == 0) failed:
>>>>>> _owner(0x0000000000000000)|_LockWord(0x0000000000000000)|_EntryList(0x0000000000000000)|_WaitSet(0x0000000000000000)|_OnDeck(0x00000000deaddead)
>>>>>>
>>>>>>
>>>>>> != 0
>>>>>>
>>>>>> Thanks,
>>>>>> David
>>>>>
>>>
>