PerfData counter: sun.gc.policy.generations in JDK 8

Srinivas Ramakrishna ysr1729 at gmail.com
Wed Jun 3 06:15:01 UTC 2015


Thanks Jon for the review and the pointer to the test. I'll get back to you later this week with a suitable test.

-- Ramki

ysr1729

> On Jun 2, 2015, at 14:16, Jon Masamitsu <jon.masamitsu at oracle.com> wrote:
> 
> Ramki,
> 
> Changes look good.
> 
> I'm guessing you tested by generating the
> perfdata by hand and verifying the contents
> of the perfdata.  Do you think a test can
> be written to verify  the change?  If you look at
> 
> test/gc/metaspace/TestMetaspacePerfCounters.java
> 
> in your repository I think that is an example that 
> can be followed.
> 
> It's a jtreg test.
> 
> http://openjdk.java.net/jtreg/
> 
> Jon
> 
>> On 06/01/2015 11:39 AM, Srinivas       Ramakrishna wrote:
>> Thanks for the review of the patch for 8-dev (from the ticket), Staffan.         
>> 
>> Sorry for the delay in getting the official webrev out -- it took me a while to first get set up with an hs9 repo (thanks Jon!) and then get my openjdk credentials updated (thanks Mark!).
>> 
>> Here's the webrev against hs9 for official review:-
>> 
>> http://cr.openjdk.java.net/~ysr/JDK-8080345/webrev.00/
>> 
>> I built and tested the change (on both 8-dev whose patch was attached with the original bug, as well as this with hs9) and verified that the counter value for generations, in the perfdata file, was now 2 instead of the previous 3.
>> 
>> thanks!
>> -- ramki
>> 
>> 
>> On Mon, May 18, 2015 at 1:22 AM, Staffan Larsen <staffan.larsen at oracle.com> wrote:
>>> Looks like a good patch to me.
>>> 
>>> /Staffan
>>> 
>>>> On 14 maj 2015, at 18:12, Srinivas Ramakrishna <ysr1729 at gmail.com> wrote:
>>>> 
>>>> https://bugs.openjdk.java.net/browse/JDK-8080345
>>>> 
>>>> 
>>>> 
>>>>> On Wed, May 13, 2015 at 1:08 PM, Srinivas Ramakrishna <ysr1729 at gmail.com> wrote:
>>>>> 
>>>>> With perm gen going away (and being replaced by metaspace) in JDK 8, it makes sense that the counter
>>>>> sun.gc.policy.generations should be "2", rather than "3". However, in JDK 8 that counter still says 3.
>>>>> As I understand, the intention was that this counter would allow you to (for example) know the range of
>>>>> the sun.gc.generation.$num.*                                           counters describing each of $num < sun.gc.policy.generations in the heap.
>>>>> Recall that the erstwhile perm gen in JDK 7 used to be synonymous with sun.gc.generation.2, but the
>>>>> JDK 8 avatars are now sun.gc.metaspace and sun.gc.compressedclassspace.
>>>>> 
>>>>> The fix is simple, and I can submit a patch. Is there an existing bug for this?
>>>>> 
>>>>> thanks!
>>>>> -- ramki
> 
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