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

[Erik Helin]

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?

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