RFR (S): 8012086: The object count event should only send events for instances occupying more than 0.5% of the heap

[Jesper Wilhelmsson]

Erik Helin skrev 8/5/13 10:00 AM:
> Jesper,
>
> On 05/07/2013 09:52 PM, Jesper Wilhelmsson wrote:
>> Erik Helin skrev 7/5/13 9:28 PM:
>>> Jesper,
>>>
>>> I've changed the flag to be an experimental flag instead of a product
>>> flag.
>>
>> Thanks!
>>
>>> Please see new webrev at:
>>> http://cr.openjdk.java.net/~ehelin/8012086/webrev.02/
>>
>> If you want to change the description of the flag to say "... to
>> generate a trace event.", I think it would read better. But either way
>> I'm fine with this change.
>
> I think that an even better description would be "... to generate a possible
> trace event", since even if the instances of the class takes up more than
> ObjectCountCutOffPercent of the used heap, there is no guarantee that an event
> will be sent (the event might be turned off).
>
> What do you think?

I think that the fact that the event might be turned off is unrelated to this 
flag and that the description would look better without the "possible".
/Jesper

>
> Thanks,
> Erik
>
>> /Jesper
>>
>>
>>>
>>> Thanks,
>>> Erik
>>>
>>> On 05/07/2013 03:54 PM, Jesper Wilhelmsson wrote:
>>>> Hi,
>>>>
>>>> Please check with the serviceability team (CC:ed) before adding a flag
>>>> to control the threshold. I suspect that they would prefer some tracing
>>>> specific way to configure these thresholds.
>>>> /Jesper
>>>>
>>>>
>>>> Erik Helin skrev 7/5/13 2:58 PM:
>>>>> Hi Bengt,
>>>>>
>>>>> thanks for the review!
>>>>>
>>>>> On 05/07/2013 11:42 AM, Bengt Rutisson wrote:
>>>>>>
>>>>>> Hi Erik,
>>>>>>
>>>>>> Looks good.
>>>>>>
>>>>>> Two minor nits:
>>>>>>
>>>>>> Could we make 0.05 into a flag or at least a declared constant?
>>>>>
>>>>> Good suggestion, I've turned into a flag: ObjectCountCutOffPercent.
>>>>>
>>>>> On 05/07/2013 11:42 AM, Bengt Rutisson wrote:
>>>>>> Could we rename _used_heap_in_words to something like
>>>>>> _total_size_in_words or _base_size_in_words since it is not really the
>>>>>> used count for the heap?
>>>>>
>>>>> Agree, I renamed it to _total_size_in_words.
>>>>>
>>>>> Please see new webrev at:
>>>>> http://cr.openjdk.java.net/~ehelin/8012086/webrev.01/
>>>>>
>>>>> Thanks,
>>>>> Erik
>>>>>
>>>>>> Thanks,
>>>>>> Bengt
>>>>>>
>>>>>> On 5/7/13 10:14 AM, Erik Helin wrote:
>>>>>>> Hi all,
>>>>>>>
>>>>>>> this change makes sure that we only send the trace event
>>>>>>> vm/gc/detailed/object_count_after_gc if the total size of all the
>>>>>>> instances of a class occupies more than 0.5% of the used heap.
>>>>>>>
>>>>>>> Webrev:
>>>>>>> http://cr.openjdk.java.net/~ehelin/8012086/webrev.00/
>>>>>>>
>>>>>>> Testing:
>>>>>>> JPRT
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Erik
>>>>>>
>>>>>>
>>>>>
>>>
>