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From Rick <ric...@gmail.com>
Subject Re: [SURVEY] How many connections are in your pool?
Date Wed, 21 Jan 2009 00:00:40 GMT
So all this being said what is the general rule of thumb for setting
up pool sizes?

On Tue, Jan 20, 2009 at 5:43 PM, Nathan Maves <nathan.maves@gmail.com> wrote:
> 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
> thread.
> Nathan
> 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
>>>>>> 50 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 made
>>>>>> 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
>>>>>> demanding projects (but again w/o long running transactions) was
just saving
>>>>>> 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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