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From "Bowler Simon" <>
Subject RE: (Pool) Pools should be self tuning
Date Wed, 22 Sep 2004 22:39:15 GMT

This is a very interesting idea, but I agree with Yoav; in that if it were implemented inside
the pool, it should be turned off by default. As well as the developer not being aware of
how the pool will behave, the gathering and analysing of statistical data is potentially resource
hungry (depending on the amount of statistical data collected and stored).

This type of feature would probably best be implemented as a utility, seperate to the pools.
It should probably take into consideration also the 'minimum' values for the pool variables.
That way, a minimum performance can be garuanteed no matter what time of the day.


Simon Bowler

-----Original Message-----
From: Shapira, Yoav []
Sent: Wednesday, 22 September 2004 10:57 PM
To: Jakarta Commons Developers List
Subject: RE: (Pool) Pools should be self tuning

IF such a thing is implemented, I'd want it turned off by default.  Your
use-case may be valid for you, but I like to make sure I know and
specify th desired behavior of my pool(s) in advance, and I wouldn't
want them to modify it by themselves.

Yoav Shapira
Millennium Research Informatics

>-----Original Message-----
>From: Stephan []
>Sent: Wednesday, September 22, 2004 2:35 AM
>Subject: (Pool) Pools should be self tuning
>I've recently discovered the package "Commons Pool" and I've played
>  GenericObjectPool. I'm attracted by all the options you can set to
>customize the behavior of the pool but after a while I started to ask
>myself. "Am I choosing sensible settings? Should I do this or should I
>do that?"
>Of course the answer depends of the usage pattern of the pool, and this
>is something that might change over time. Conclusion: I will probably
>never know what's the useage patern of a pool and I don't want to guess
>To solve this problem, in my opinion, the pool should be self tunning.
>Just like the Evictor thread (which is just a trigger), another thread
>would wakeup at regular intervals and gather statistical data and
>analyse it. As a result action would be taken (like changing the values
>of the pool settings) to adapt the pool to the usage pattern.
>How you you go about monitoring the usage pattern of a pool?
>The only ideas I have right now is using a moving average of the active
>connections and may be remembering this average throught the day so
>  the pool that anticipate usage. Imagine an automatic process that
>the pool once a day at 1:00 and borrows 1000 objects from the pool in a
>few seconds: The pool could anticipate this regular usage and create
>more objects in the pool.
>I'm not very good at statistics and I hope that some of you are and
>could explain how statistics could help in this task.
>This self tuning thing could be a more general problem and find other
>applications in other pagakges.
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