RFR (S) 8185590: ShouldNotReachHere from ClassLoaderData::try_get_next_class()

[coleen.phillimore at oracle.com]

On 8/1/17 3:30 PM, Zhengyu Gu wrote:
>
>
> On 08/01/2017 12:53 PM, coleen.phillimore at oracle.com wrote:
>>
>>
>> On 8/1/17 12:08 PM, Zhengyu Gu wrote:
>>>
>>>
>>> On 08/01/2017 11:57 AM, coleen.phillimore at oracle.com wrote:
>>>>
>>>>
>>>> On 8/1/17 11:03 AM, coleen.phillimore at oracle.com wrote:
>>>>>
>>>>>
>>>>> On 8/1/17 10:45 AM, Zhengyu Gu wrote:
>>>>>> How about setup a marker before entering the loop, ensure the loop
>>>>>> won't come back to initial entry?
>>>>>
>>>>> It's ok for the loop to get back to the initial entry though.... if
>>>>> there are less classes than the count in compilationPolicy.
>>>>
>>>> Sorry, I'm wrong about this.  Maybe this makes sense too, but not 
>>>> as an
>>>> assert but as a terminating condition.
>>>
>>> If InstanceKlass::number_of_instance_classes() counting is right, then
>>> the two termination conditions are equivalent, right?
>>
>> Yes.  Is this a code review?
>
> Reviewed.

Thank you!
Coleen

>
> -Zhengyu
>
>> thanks,
>> Coleen
>>
>>>
>>> Thanks,
>>>
>>> -Zhengyu
>>>
>>>>
>>>> Coleen
>>>>
>>>>>
>>>>> Coleen
>>>>>>
>>>>>> #ifdef ASSERT
>>>>>>   Klass* starting_class_entry = _current_class_entry;
>>>>>> #endif
>>>>>>
>>>>>>   for (int i = 0; i < max_classes; ) {
>>>>>>
>>>>>>   ....
>>>>>>
>>>>>>      ASSERT(_current_class_entry != starting_class_entry, ....)
>>>>>>    }
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> -Zhengyu
>>>>>>
>>>>>>
>>>>>> On 08/01/2017 10:32 AM, coleen.phillimore at oracle.com wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 8/1/17 10:23 AM, Aleksey Shipilev wrote:
>>>>>>>> On 08/01/2017 04:18 PM, coleen.phillimore at oracle.com wrote:
>>>>>>>>> Summary: Counting number of instanceKlass code didn't work.
>>>>>>>>>
>>>>>>>>> A late code review change caused this regression. Tested with
>>>>>>>>> internal NSK mlvm tests with
>>>>>>>>> -XX:-TieredCompilation -XX:CompileThreshold=100 including the one
>>>>>>>>> where I reproduced the failure
>>>>>>>>> overnight.
>>>>>>>>>
>>>>>>>>> open webrev at
>>>>>>>>> http://cr.openjdk.java.net/~coleenp/8185590.01/webrev
>>>>>>>> Hm, so now that the loop variable is _conditionally_ incremented,
>>>>>>>> what
>>>>>>>> guarantees the loop termination?
>>>>>>>
>>>>>>> The fact that number_of_classes can't be zero so something has 
>>>>>>> to be
>>>>>>> returned?
>>>>>>>
>>>>>>> I had trouble coming up with something better.  If you have a good
>>>>>>> idea,
>>>>>>> I'll change it.
>>>>>>>
>>>>>>> thanks!
>>>>>>> Coleen
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> -Aleksey
>>>>>>>>
>>>>>>>
>>>>>
>>>>
>>