does anyone know whether ActiveRecord has supported connection pool?

rubyonrails-talk
1

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.

2

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

3

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?

4

No, just one connection.

5

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?

6

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....

7

thanks for great suggestion :slight_smile:

8

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

9

thank you very much.

10

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?

11

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: