Adaptiveness of adaptive sizing

Alex Aisinzon aaisinzon at
Fri Mar 14 23:36:18 UTC 2008


I thank you for your feedback. Our apps like memory and we tend to let
them use as much as possible, even at the cost of some infrequent longer
Therefore, I do not think that there is an interest in dynamically
managing the size of the generations within their limits.
In that light, I do not want to bother you by asking clarifications on
techniques I will most likely not use.


Alex A 

-----Original Message-----
From: Jon.Masamitsu at Sun.COM [mailto:Jon.Masamitsu at Sun.COM] 
Sent: Friday, March 14, 2008 4:18 PM
To: Alex Aisinzon
Cc: hotspot-gc-use at
Subject: Re: Adaptiveness of adaptive sizing


The adaptive size policy does not currently move space between
the tenured generation and the nursery. Rather the adaptive
size policy grows and shrink each generation within their
specified minimum and maximum sizes to try an achieve a
user specified pause time goal and throughput goal. Given
that fact, are you still interested in more details on how
the adaptive size policy makes it's decisions?


Alex Aisinzon wrote On 03/14/08 15:06,:

> Hi
> Our application has a lot of long lived objects (large session,
> cache,..).
> The size of the tenured space grows through the usage period
> (typically work hours) and then goes down as users log out.
> Typically, a JVM supporting 600 concurrent users could have 600-800MB
> of rock bottom long lived objects in the tenured.
> I am interested in exploring the adaptive sizing policy. Nevertheless,
> since the tenured grows during the day, I wonder if the adaptive
> sizing policy will adapt the tenured and nursery spaces dynamically.
> Finally, I wonder which metrics an adaptive sizing policy uses to find
> the "optimal" ratio between nursery and tenured.
> We are using the Sun JDK 1.5 for now.
> Thanks in advance
> Alex Aisinzon
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