RFR - [RFE] JDK-8007141 : Introduce Dynamic MBean exposing the perf counters

[Harsha Wardhana B]

Perfcounter are dynamic and can change. Applications must be aware of 
that and work around it.

Perf counters being dynamic must be documented and must not be a 
deterrent for consuming them (via Dymanic MBean).

Regards

Harsha


On Monday 27 February 2017 11:22 PM, Erik Gahlin wrote:
> If somebody writes a tool that plots the values that the perf counters 
> provide, which is bound to happen if it is exposed via JMX, but then 
> the internals of the JVM is changed and the perf counter value is 
> removed or it is incorrect.
>
> Erik
>
>> Hi Erik,
>>
>> I am not sure if Perf Counters could be disabled. If yes, then 
>> PerfCounter MBean must throw appropriate exception while getting 
>> MBeanInfo.
>>
>> I don't know about tests for PerfCounter. The webrev contains tests 
>> for PerfCounter MBean.
>>
>> I am not sure how we will be breaking other's code. Could you please 
>> elaborate?
>>
>> Thanks
>> Harsha
>>
>> On Monday 27 February 2017 07:39 PM, Erik Gahlin wrote:
>>> Hi Harsha,
>>>
>>> How will perf counters be supported?
>>>
>>> Can they be removed at anytime, or only at major releases etc. Do we 
>>> have tests for them? I think it would be good know, and perhaps 
>>> state somewhere so we don't break people's code.
>>>
>>> Erik
>>>
>>>> Hi All,
>>>>
>>>> Please review the below RFE,
>>>>
>>>> JDK-8007141 <http://JDK-8007141> : Introduce Dynamic MBean exposing 
>>>> the perf counters.
>>>>
>>>> with webrev at,
>>>>
>>>> http://cr.openjdk.java.net/~hb/8007141/webrev.00/
>>>>
>>>> Appreciate if I can get inputs for below.
>>>>
>>>> 1. Location of HotSpotPerfCounterMBean. It is located at 
>>>> src/jdk.management/share/classes/com/sun/management/internal. It 
>>>> can be moved to src/jdk.management/share/classes/com/sun/management 
>>>> if required.
>>>>
>>>> 2. Javadoc comments for HotSpotPerfCounterMBean. Not sure if it is 
>>>> adequate.
>>>>
>>>> 3. Description for each attribute of MBean. I am using getUnits(), 
>>>> getVariability(), and getFlags() for description. I am not sure if 
>>>> that is the right description. Appreciate inputs from someone who 
>>>> knows perf counters well.
>>>>
>>>> Thanks
>>>>
>>>> Harsha
>>>>
>>>>
>>>
>>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/serviceability-dev/attachments/20170228/15cbb7f5/attachment-0001.html>