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

[Zhengyu Gu]

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.

-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
>>>>>>>
>>>>>>
>>>>
>>>
>