RFR(S): 8163994: Nightly test crashed in jvmtiAllocate

[serguei.spitsyn at oracle.com]

Thanks, Dmitry!
Serguei


On 9/1/16 03:55, Dmitry Samersoff wrote:
> Serguei,
>
> OK. Closing as a dup.
>
> -Dmitry
>
> On 2016-09-01 13:40, serguei.spitsyn at oracle.com wrote:
>> Hi David,
>>
>> Thank you for the comment.
>>
>> Dmitry,
>>
>> It seems, Chris and David are not comfortable with current fix.
>> Are you Ok to close this bug as a dup?
>>
>> Thanks,
>> Serguei
>>
>>
>> On 8/29/16 20:05, David Holmes wrote:
>>> Hi Serguei,
>>>
>>> On 30/08/2016 4:46 AM, serguei.spitsyn at oracle.com wrote:
>>>> Chris and David,
>>>>
>>>> We had a private discussion about this bug with Dmitry last week.
>>>> I initially suggested to close it as a dup of JDK-8134103 but then
>>>> agreed with a fix replacing crash symptom with AGENT_ERROR_INTERNAL.
>>>> I still have some doubt if it makes sense, as it does not look as
>>>> important.
>>>>
>>>> Now, it seems you also prefer to close this bug as a dup.
>>>> But let's check your opinion on the Dmitry's reasoning below.
>>> The problem is that the "fix" still doesn't guarantee that we will get
>>> the more informative AGENT_ERROR_INTERNAL. The whole situation is racy.
>>>
>>> But I won't block it and don't want to waste time arguing over it. So
>>> if Dmitry wants to proceed then you can count this as Reviewed.
>>>
>>> Thanks,
>>> David
>>> -----
>>>
>>>> Thanks,
>>>> Serguei
>>>>
>>>>
>>>> On 8/29/16 06:12, Dmitry Samersoff wrote:
>>>>> Chris & David,
>>>>>
>>>>> JVMTI_ERROR_WRONG_PHASE problem is complicated and requires significant
>>>>> work probably on both JDWP and JVMTI side. Serguei plan to do it as a
>>>>> part of JDK-8134103 and not for JDK 9.
>>>>>
>>>>> So yes, we can close this one as a dup of JDK-8134103 - it has the same
>>>>> root cause and should be addressed as the part of JDK-8134103
>>>>> (particularly, we have to cleanup ignore_vm_death logic)
>>>>>
>>>>> But the crash is observed only once in a nightly, so my intention is to
>>>>> save us a bit of time next time when this situation happens.
>>>>>
>>>>> i.e. before the changes we get JVMTI_ERROR_WRONG_PHASE message and
>>>>> *crash*, after the changes  we get JVMTI_ERROR_WRONG_PHASE message
>>>>> and AGENT_ERROR_INTERNAL message.
>>>>>
>>>>>
>>>>> -Dmitry
>>>>>
>>>>>
>>>>>
>>>>> On 2016-08-29 09:43, Chris Plummer wrote:
>>>>>> On 8/28/16 6:14 PM, David Holmes wrote:
>>>>>>> On 27/08/2016 7:35 AM, Chris Plummer wrote:
>>>>>>>> Hi Dmitry,
>>>>>>>>
>>>>>>>> Although the fix is addressing the specific issue described in the
>>>>>>>> bug,
>>>>>>>> what about the general issue of referencing gdata after a call to
>>>>>>>> cbEarlyVMDeath(). Do more references to gdata need to be protected?
>>>>>>>>
>>>>>>>> Also, is there the possibility of a multi-threading race condition
>>>>>>>> here?
>>>>>>>> Could gdata be cleared by another thread after it is checked?
>>>>>>> Certainly. This really isn't fixing anything just adding a bailout
>>>>>>> check before the crashing code. We can still crash and not be any the
>>>>>>> wiser as to why.
>>>>>>>
>>>>>>> Not sure I really see the point of doing this instead of closing this
>>>>>>> as a dup of JDK-8134103 and fixing things properly.
>>>>>> It it correct to say that Dmitry is fixing a bug exposed by
>>>>>> JDK-8134103,
>>>>>> or that he is temporarily working around something that is not a true
>>>>>> bug, but is indirectly caused by JDK-8134103. I'm not sure, but the
>>>>>> answer will dictate the correct course of action here.
>>>>>>
>>>>>> Chris
>>>>>>> David
>>>>>>>
>>>>>>>> thanks,
>>>>>>>>
>>>>>>>> Chris
>>>>>>>>
>>>>>>>> On 8/26/16 4:00 AM, Dmitry Samersoff wrote:
>>>>>>>>> Everybody,
>>>>>>>>>
>>>>>>>>> Please review the fix.
>>>>>>>>>
>>>>>>>>> http://cr.openjdk.java.net/~dsamersoff/JDK-8163994/webrev.02/
>>>>>>>>>
>>>>>>>>> *Problem*
>>>>>>>>>
>>>>>>>>> Under some circumstances, when JVMTI_ERROR_WRONG_PHASE(112) is
>>>>>>>>> received,
>>>>>>>>> jvmtiAllocate could be called after call to cbEarlyVMDeath.
>>>>>>>>>
>>>>>>>>> cbEarlyVMDeath set gdata->jvmti to NULL, so jvmtiAllocate crashes.
>>>>>>>>>
>>>>>>>>> The problem appears only once in nightly testing and I was not
>>>>>>>>> able to
>>>>>>>>> reproduce it locally.
>>>>>>>>>
>>>>>>>>> *Solution*
>>>>>>>>>
>>>>>>>>> Guard added to jvmtiAllocate to get meaningful error message
>>>>>>>>> instead of
>>>>>>>>> crash.
>>>>>>>>>
>>>>>>>>> These fix doesn't fix root cause - JVMTI_ERROR_WRONG_PHASE
>>>>>>>>> problem is
>>>>>>>>> going to be addressed under JDK-8134103.
>>>>>>>>>
>>>>>>>>> -Dmitry
>>>>>>>>>
>