Rails core - Nov 2012 - Feature Request: Add support for multiple, concurrent, connection pools

Since, https://github.com/rails/rails/issues/8344 was closed, raising this 
here:

see: 
http://stackoverflow.com/questions/13598583/active-record-and-multi-threading-involving-multiple-dbs

I have a Rails app that is multi homed.

foo.mysite.com talks to the "foo" db.

bar.mysite.com talks to the "bar" db.

This is accomplished by calling:

ActiveRecord::Base.connection_handler.establish_connection("ActiveRecord::Base",
foo_spec)

When requests come in for foo it uses the foo_spec, when requests come in 
for bar it uses the bar_spec.

Everything is happy and there is peace in the world.

However,

I also use sidekiq, it is heavily multi-threaded.

I was getting weird behavior in sidekiq. Often when I thought I was talking 
to the foo_db,ActiveRecord::Base.connection was pointed at bar_db.

I dug into the code and found:

 def retrieve_connection_pool(klass)
    pool = @class_to_pool[klass.name]
    return pool if pool
    return nil if ActiveRecord::Base == klass
    retrieve_connection_pool klass.superclass
  end

Turns out the internal design of AR only allows AR::Base to know about a 
single connection pool.

Is there any way to get thread 1 to talk to db1, and thread 2 to talk to a 
db2 at the same time, usingActiveRecord::Base.connection ?

Am I missing something about the design? Has anything changed in 4?

I do not really want to have to resort to adding a "special" base
class
that adds this, as I would be risking certain gems that talk to
ActiveRecord::Base.connection
breaking. 


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