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From S Ahmed <sahmed1...@gmail.com>
Subject Re: tomcat jdbc pool, creating a pool of pools, single connection memory footprint
Date Wed, 30 May 2012 21:23:26 GMT
Chris,

Great thanks that is exactly what I was looking for, just to get an idea at
this point.

And yes it was for mysql.

I was thinking one could create a smarter pool, one that created more
connections for sites used more often, and less for others.

Much appreciated.

On Wed, May 30, 2012 at 10:07 AM, Christopher Schultz <
chris@christopherschultz.net> wrote:

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> Ahmed,
>
> On 5/29/12 9:29 AM, S Ahmed wrote:
> > If my requirement for a hosted application is to give each
> > customer a separate instance of mysql, I am curious how feasible
> > that would be.
>
> You can certainly do this.
>
> > What is the memory footprint for a single connection to a
> > database?
>
> That depends a lot of which database you are using (MySQL connections
> are fairly modest: the "retained size" of one of my MySQL
> JDBC4Connection objects is 66k in an x86-64 environment with a 64-bit
> Sun/Oracle JVM), what things you are having cached/pooled on the
> client side, etc. You'd have to give us a lot more information about
> your environment. Better yet, configure it the way you want it and use
> a profiler to see how "big" the connections become.
>
> > If I had 10K separate mysql instances, would it be feasible to
> > create a pool of pools? i.e. a hashmap of connection pools?
>
> That sounds like a lot of MySQL instances to be contacted by a single
> application server. Do you need 10k separate customers all running in
> the same webapp?
>
> 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?
>
> - -chris
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