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

[Zhengyu Gu]

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?

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
>>>>>
>>>>
>>
>