Survivor space class historgram print (know your bad garbage)

[Alexey Ragozin]

Hi Michal,

This is not exactly what you are asking for, but you may find it useable.

Take a look at sjk hh command (https://github.com/aragozin/jvm-tools#hh).

With -dead option it will print you histogram of garbage in your heap
(underhood it take normal jmap-style histogram then forces GC then
takes another histogram and calculates diff).

I have found you very useful for analyzing "garbage" problem.

Another feature sjk helping with memory troubleshooting - reporting
per thread allocation rate in real time (JMX is used underhood).

Regards,
Alexey

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
> P?edmet: 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
>>>
>>> > ______________________________
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>>> > hotspot-gc-use at openjdk.java.net
>>> > http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
>>> >
>>> >
>>
>>
>> >
>> >
>> >
>>
>> > _______________________________________________
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>>
>>
>