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

[coleen.phillimore at oracle.com]

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?
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
>>>>>>
>>>>>
>>>
>>