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From "Nathan Maves" <nathan.ma...@gmail.com>
Subject Re: [SURVEY] How many connections are in your pool?
Date Tue, 20 Jan 2009 22:43:14 GMT
I am no expert in this either but a default setup for oracle allows for 200
connections.  At least this was the case a few version back.  In my mind I
think you can an maybe should have more connections than processors.
 Depending on the length of time the connection is open and idle.  Again I
could be very wrong on this so I hope others continue to input on this

On Tue, Jan 20, 2009 at 2:22 PM, Sundar Sankar <fatboysuns@gmail.com> wrote:

> Thanks Nicholoz!
>                                 I have never ever questioned people for
> having so many connections. But that was the reason what I have always got,
> i.e,  Connections being propotionate to number of parallel users. I just
> brought the question about because, I wasnt surprised at all when Clinton
> mentioned 600 connections in the pool.
> -S
> On Tue, Jan 20, 2009 at 1:12 PM, Nicholoz Koka Kiknadze <
> kiknadze@gmail.com> wrote:
>> Hi Sundar,
>> I am not an hardware expert, but I suspect that even with modern dma
>> access etc if you ask your CPU to process N database transactions (initiated
>> by different users) in parallel it may take longer compared to when you ask
>> it to do them consequently. So quite possible that pools with connection
>> number > CPU number induce performence penalties. In other words the time
>> your pool waits for a connection to get available in the pool is just caused
>> by your hardware (CPU) beeing busy, so why add extra latency with extra pool
>> code...
>> Again, of course the logic can not applyed to long running transactions
>> when CPU is idling in the midst of transaction waiting for e.g. extra user
>> input.
>> On Tue, Jan 20, 2009 at 2:50 PM, Sundar Sankar <fatboysuns@gmail.com>wrote:
>>> Hi Clinton,
>>>                   I apologize ahead, if I am missing or not getting
>>> something right. As far as my understanding goes, arent number of
>>> connections in a pool in relation to the number of parallel users that
>>> access the application than the number of CPU cores in a database?
>>> Regards
>>> S
>>> On Tue, Jan 20, 2009 at 12:39 PM, Clinton Begin <clinton.begin@gmail.com
>>> > wrote:
>>>> It sounds like you're still using a "pool", but your max, min, idle, and
>>>> active connections are all equal (i.e. 16).  Otherwise, how do you allocate
>>>> connections to the incoming requests?
>>>> Cheers,
>>>> Clinton
>>>> On Tue, Jan 20, 2009 at 12:33 PM, Nicholoz Koka Kiknadze <
>>>> kiknadze@gmail.com> wrote:
>>>>> Ours is an application that requires guaranteed response times under
>>>>> ms, so:
>>>>> 1) We dropped using any kind of pool, so that
>>>>> 2) number of constantly open connections equals to the number of
>>>>> processors (16)
>>>>> 3) I know you were asking about pool, but still I dared to respond with
>>>>> this no-pool variant because I think maybe what you are asking can be
>>>>> reformulated as: is there any use of DB pool in a short lived transaction
>>>>> scenario, or its better to have one connection per CPU. Testing our app
>>>>> us to drop using pool with TimesTen (in memory) database. Now I started
>>>>> suspect that using using db pool (I've mostly used dbcp ) in other less
>>>>> demanding projects (but again w/o long running transactions) was just
>>>>> development time (let pool handle concurrency issues), but not any
>>>>> substantial performance gain. Wonder what others think...
>>>>> On Tue, Jan 20, 2009 at 8:43 AM, Clinton Begin <
>>>>> clinton.begin@gmail.com> wrote:
>>>>>> Hi all,
>>>>>> I've been studying a few large enterprise applications and have
>>>>>> noticed an interesting trend... many of these apps have HUNDREDS
>>>>>> connections (like 600) available or even open in their connection
>>>>>> Survey Questions:
>>>>>>   1. How many connections do you have available in your pool?
>>>>>>   2. And if you know, how many CPU cores are available on your
>>>>>> database server (or cluster)?
>>>>>>   3. If you have 2x or 3x more connections than you do CPUs, do you
>>>>>> have a reason that you could share?
>>>>>> Cheers,
>>>>>> Clinton

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