Ruby Forum Ruby on Rails > does anyone know whether ActiveRecord has supported connection pool?

Posted by Kang Peng (Guest)
on 16.11.2008 05:12
(Received via mailing list)
does anyone know whether ActiveRecord has supported connection pool? i
can't find articles talking about this, if so how to control it in
Rails apps.

thanks a lot.
Posted by Jeremy Kemper (Guest)
on 16.11.2008 05:29
(Received via mailing list)
On Sat, Nov 15, 2008 at 8:11 PM, Kang Peng <okgoodsun@gmail.com> wrote:
> does anyone know whether ActiveRecord has supported connection pool? i
> can't find articles talking about this, if so how to control it in
> Rails apps.

In Rails 2.1 and earlier, Active Record uses a single persistent
connection per thread.

Beginning in Rails 2.2, Active Record uses a connection pool. Install
the 2.2rc2 release and give it a spin.

Best,
jeremy
Posted by kang peng (Guest)
on 16.11.2008 07:19
(Received via mailing list)
thanks. so before Rails2.2, each request will open new connection to
database according to 'Active Record uses a single persistent
connection per thread'? because as i know, each request will start a new
thread, is it correct?
Posted by Jeremy Kemper (Guest)
on 16.11.2008 12:25
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No, just one connection.
Posted by kang peng (Guest)
on 16.11.2008 14:25
(Received via mailing list)
ok, so i think ActiveRecord is thread safe, right? if so, each request 
which
call to database will be processed one by one, not concurrent, this 
seems
RoR's will be not good when faces big amont of requests in a short time. 
is
it ture?
Posted by Robert Walker (robert4723)
on 17.11.2008 00:37
kang peng wrote:
> ok, so i think ActiveRecord is thread safe, right? if so, each request 
> which
> call to database will be processed one by one, not concurrent, this 
> seems
> RoR's will be not good when faces big amont of requests in a short time. 
> is
> it ture?

Do you have a scaling problem right now? If not then worry about this 
when you do....

http://gettingreal.37signals.com/ch04_Scale_Later.php
Posted by kang peng (Guest)
on 17.11.2008 04:23
(Received via mailing list)
thanks for great suggestion :)

On Mon, Nov 17, 2008 at 7:37 AM, Robert Walker <
Posted by Jeremy Kemper (Guest)
on 17.11.2008 07:14
(Received via mailing list)
Right. You need to use a nonblocking database driver to do concurrent 
requests.

You can do this with neverblock's database drivers and Active Record
adapter (http://www.espace.com.eg/neverblock/benchmarks) or with
jruby.

Best,
jeremy
Posted by kang peng (Guest)
on 17.11.2008 08:11
(Received via mailing list)
thank you very much.
Posted by boblu (Guest)
on 17.11.2008 08:32
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Can anybody tell me about this?
Does this "connection pool" have something to do with multiple
database connection?
Or it is only for concurrent access with one database?
Posted by Jonathan Rochkind (jrochkind)
on 24.11.2008 22:56
It has to do with multiple connections to one database.

It has, however, always been possible to have some models living in one 
database, and others living in others, if that's what you want. 
Relationships accross databases don't always work perfectly, if you're 
trying to do fancy things. (Like, pre-loading a relationship accross 
databases).

For using multiple databases in your app, see:

http://wiki.rubyonrails.org/rails/pages/HowtoUseMultipleDatabases

Incidentally, even pre Rails 2.2, I have had success using multiple 
connections to a single db in different threads, using the mysql gem 
adapter. Now I wonder if the mysql gem adapter is actually non-blocking 
though, or if my different threads were still blocking on db access.

Jonathan

boblu wrote:
> Can anybody tell me about this?
> Does this "connection pool" have something to do with multiple
> database connection?
> Or it is only for concurrent access with one database?