Rails - Apr 2010 - How many connection pool should we have for internet facing apps?

Hi all,

This is a rather basic question about connection pooling in ruby on
rails. In rails we can define the connection pool in database.yml. I
assume it is quite safe to hardcode this value for intranet
application since we would know how many users that will be using the
apps. But for an internet facing apps where we don''t know how many
users that will be accessing the app, how many connection pool should
we provide ? Can anyone share their experience on this to enlighten
me?

Thank you very much in advance for the insights.

Kind regards,
Joshua

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On Apr 29, 1:57 am, Joshua Partogi
<joshua.part...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Hi all,
>
> This is a rather basic question about connection pooling in ruby on
> rails. In rails we can define the connection pool in database.yml. I
> assume it is quite safe to hardcode this value for intranet
> application since we would know how many users that will be using the
> apps. But for an internet facing apps where we don''t know how many
> users that will be accessing the app, how many connection pool should
> we provide ? Can anyone share their experience on this to enlighten
> me?
Connection pool size isn''t really related to number of users. It
doesn''t really make much difference without a multithreaded setup (and
your default ''normal'' ruby + passenger or mongrel
isn''t one of those)

Fred
>
> Thank you very much in advance for the insights.
>
> Kind regards,
> Joshua
>
> --http://twitter.com/scrum8
>
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Frederick Cheung wrote:
>On Apr 29, 1:57 am, Joshua Partogi 
><joshua.part...->Re5JQEeQqe8AvxtiuMwx3w-XMD5yJDbdMReXY1tMh2IBg@public.gmane.org>
wrote:
>> Hi all,
>>
>> This is a rather basic question about connection pooling in ruby on
>> rails. In rails we can define the connection pool in database.yml. I
>> assume it is quite safe to hardcode this value for intranet
>> application since we would know how many users that will be using the
>> apps. But for an internet facing apps where we don''t know how
many
>> users that will be accessing the app, how many connection pool should
>> we provide ? Can anyone share their experience on this to enlighten
>> me?
>
>Connection pool size isn''t really related to number of users. It
>doesn''t really make much difference without a multithreaded setup
(and
>your default ''normal'' ruby + passenger or mongrel
isn''t one of those)
Fair enough, in the default state with passenger, you have a multi-process 
setup, and since each process is independent, they don''t know of each
other,
and thus the value for connection in the database.yml file is more or less 
meaningless. (It is good to be explicit in explainging why this is the 
case).

Nevertheless, the database itself may have a limited connection pool, rather 
than using the standard UNIX model of fork a new process on connection, or 
othewrwise put a user-configurable constraint on number of active 
connections. (I undertsand that MySQL often has such a limit.) Any guidance 
for the original poster on how best to deal with that? 


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On Apr 30, 6:52 pm, "Joe Smith"
<unknown_kev_...-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org>
wrote:
> Frederick Cheung wrote:
> >On Apr 29, 1:57 am, Joshua Partogi
>
><joshua.part...->Re5JQEeQqe8AvxtiuMw...-XMD5yJDbdMReXY1tMh2IBg@public.gmane.org>
wrote:
> >> Hi all,
>
> >> This is a rather basic question about connection pooling in ruby
on
> >> rails. In rails we can define the connection pool in database.yml.
I
> >> assume it is quite safe to hardcode this value for intranet
> >> application since we would know how many users that will be using
the
> >> apps. But for an internet facing apps where we don''t know
how many
> >> users that will be accessing the app, how many connection pool
should
> >> we provide ? Can anyone share their experience on this to
enlighten
> >> me?
>
> >Connection pool size isn''t really related to number of users.
It
> >doesn''t really make much difference without a multithreaded
setup (and
> >your default ''normal'' ruby + passenger or mongrel
isn''t one of those)
>
> Fair enough, in the default state with passenger, you have a multi-process
> setup, and since each process is independent, they don''t know of
each other,
> and thus the value for connection in the database.yml file is more or less
> meaningless. (It is good to be explicit in explainging why this is the
> case).
>
> Nevertheless, the database itself may have a limited connection pool,
rather
> than using the standard UNIX model of fork a new process on connection, or
> othewrwise put a user-configurable constraint on number of active
> connections. (I undertsand that MySQL often has such a limit.) Any guidance
> for the original poster on how best to deal with that?
Well if your database has a limit on the number of connections, ensure
that it''s greater than the number of mongrels/passenger instances
(and if you''re going to actually be using the connection pooling stuff
i suppose you''d want to make it greater than the sum of the size of
the connection pool across application instances). I seem to remember
the default limit on mysql is 100, but it can go way higher than that
(and if you are going to have several hundred mongrels you can
probably afford a big beefy database server too)

Fred
>
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