Survivor space class historgram print (know your bad garbage)

[Srinivas Ramakrishna]

Hi Michal --

That code was at that time internal to Sun/Oracle and was not integrated
into the product for the reasons I described. Since Tony and I are now both
outside of Oracle, I don't know if the code was kept or lost. If it is
there, perhaps someone inside Oracle could help with it, especially if it's
in Mission Control in some form. Don't know because AFAIK that's a for fee
product and code may not necessarily be open source (most likely not).

You should be able to look at the age table interface and build the
functionality into your JVM if you wanted. If you are a source licensee,
and the support models are what they used to be, you'd be able to talk with
your Oracle liaison to get further help. You can look at the code that does
age table updates while copying survivor objects to see how it's done. I
can't recall how the original was done (and even if I did, I couldn't
describe code that is not open source and which i was privy to while a
Sun/Oracle employee, nor can I provide actual help to you unless the code
was open sourced), but you can think of how you might do that census over
the population of interest to you at a time of interest to you and do it
accordingly.

all the best!
-- ramki



On Tue, Nov 5, 2013 at 2:26 AM, Michal Frajt <michal at frajt.eu> wrote:

>  Hi Ramki,
>
> We have again a situation where the survivor space histogram would help
> us to clarify an application behavior. Would you be able to find the
> non-integrated code reporting the survivor space class histogram on every
> minor collection run? We are maintaining our own openjdk version where we
> would simply try to integrate it again. I assume that the code was extended
> around the ageTable class.
>
> Thanks,
> Michal
>
> Od: hotspot-gc-dev-bounces at openjdk.java.net
> Komu: "Tony Printezis" tony.printezis at oracle.com
> Kopie: hotspot-gc-use at openjdk.java.net
> Datum: Thu, 17 Nov 2011 08:53:32 -0800
> Předmet: Re: Survivor space class historgram print (know your bad garbage)
>
> > Yes, that seems like a good place to expose such functionality. The
> question of refactoring to allow
> > the stats gathering to happen at low cost when disabled of course still
> remains, I guess.
>
> > thanks!
> > -- ramki
>
> > On Thu, Nov 17, 2011 at 5:10 AM, Tony Printezis <
> tony.printezis at oracle.com> wrote:
>
>> >
>> > No current plans to integrate this. But this is something we could
>> consider as part of our ongoing effort to support Mission Control.
>> >
>> > Tony
>>
>> >
>> > On 11/16/2011 7:01 PM, Srinivas Ramakrishna wrote:
>>
>> AFAR, it was not integrated at that time because of the performance
>> impact even when the feature was turned off.
>> > I believe it would be possible to refactor the code, at some cost, to
>> get this to work without that performance
>> > impact, but that didn't get done. It might be time to revisit that code
>> and do the requisite refactoring. Tony et al?
>> >
>> > -- ramki
>> >
>> >
>> >
>> > On Wed, Nov 16, 2011 at 3:45 PM, Michal Frajt <michal at frajt.eu> wrote:
>> >
>>>
>>> >
>>> >
>>>
>>> > Hi,
>>>
>>> >
>>>
>>> > Is there a way to get printed a survivor space class histogram on
>>> every minor collection run? Tony once provided us a special jdk build
>>> containing this feature but it got never integrated as a print flag into
>>> the main hotspot version. It was very useful for understanding and
>>> identifying promoted objects to the old gen. Additionally we were looking
>>> to get a class histogram print for the eden space but there was no easy way
>>> to implement it. The eden space class histogram would help to identify
>>> garbage invoking minor collection runs. It could be as well used to check
>>> the impact of the scalar replacements.
>>>
>>> >
>>>
>>> > Would it be possible to reimplement both histogram prints?
>>>
>>> >
>>>
>>> > Thanks,
>>>
>>> > Michal
>>>
>>> > _______________________________________________
>>> > hotspot-gc-use mailing list
>>> > hotspot-gc-use at openjdk.java.net
>>> > http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
>>> >
>>> >
>>
>>
>> >
>> >
>> >
>>
>> > _______________________________________________
>> hotspot-gc-use mailing listhotspot-gc-use at openjdk.java.nethttp://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
>>
>>
>
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