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Date: Thu, 31 May 2012 00:18:46 +0200
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To: Tomcat Users List <users@tomcat.apache.org>
Subject: Re: tomcat jdbc pool, creating a pool of pools, single connection
 memory footprint
References: 
 <CAG2rwuN+SoSJz==-ZWxZmT-Q0t=AEeqvYhHR7bewcuGFLMjZNg@mail.gmail.com>
 <4FC629BF.9010703@christopherschultz.net>
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> 
> On Wed, May 30, 2012 at 10:07 AM, Christopher Schultz <
> chris@christopherschultz.net> wrote:
..
>>
>> If my environment and requirements match yours, you'd need 10000 *
>> max_pool_size * 66KiB at peak usage. That's about 640MiB for each
>> connection you want in 10k pools. For a (uniform) max pool size of 4,
>> you'll need more than 2GiB of heap space just for connection pools.
>>
>> Is that acceptable?
>>

Taking the same hypothetical case and figures :

Assuming that you need a total of (10000 * 4 connections) = 40000 connections.
Assuming that it takes 10ms to set up one such connection, and that once it is there, you 
don't do anything with it and just let it be for now.
Assuming we ignore such things like bandwidth, other things happening on that host etc..
It then takes a total of (10 ms * 40000) = 400000 ms = 400s = ~ 6.5 minutes
just to set up these connections.

Is that acceptable ?

What I mean is that once you start playing with such numbers, you may want to look at 
other aspects than just required memory..

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