record object number in AgeTable for G1

臧琳 zanglin5 at
Wed Jan 16 01:29:50 UTC 2019

Hi Thomas, 
      Thanks for your suggestion, I will try to get some performance number. 
      Btw, do you have any recommendation of the benchmark/micro-bench for pause time measurement? 

-----Original Message-----
From: Thomas Schatzl <thomas.schatzl at> 
Sent: Tuesday, January 15, 2019 5:04 PM
To: 臧琳 <zanglin5 at>; hotspot-gc-dev at
Subject: Re: record object number in AgeTable for G1


On Tue, 2019-01-15 at 02:26 +0000, 臧琳 wrote:
> Hi all, 
>         I recently worked with G1 and found that the AgeTable records 
> the number of bytes for every age. But it is hard to get the object 
> count for every age, I think it may be useful when I want to know how 
> is the object distribution looks like for every age. so I made a patch 
> to make AgeTable record the object count.
>         do you think it is a reasonable change?

  in such cases, i.e. changes to the core evacuation method, the problem is typically not so much adding information, but weighing the impact on pause times vs. the gain.

I.e. such a change would need to be thoroughly performance-tested.


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