When should I create Solr connection in a Rails app

Question

I'm accessing Solr in a Ruby on Rails application by using rsolr (not Sunspot). I create the local solr object that I use to send requests like this:

solr = RSolr.connect(:url => "http://localhost:8983/solr")

as far as I understand, this is not really a connection but just an object that will issue requests on demand, so it shouldn't be expensive to keep it initialized and it should never disconnect. According to that, it should be ok to have one global solr object, create it at start time and forget about it. Right? But maybe it's not thread safe?

When should I create the solr connection?

Answer 1

All that the RSolr.connect method really does is sanitize and save the options that you're using. You can see that method here. It's passed a new connection object (which, notably, doesn't have an initialize method, so it's not doing anything when created) and the options that you pass to RSolr.connect.

So yes, you're right -- no harm at all in connecting once and leaving it connected forever hanging around in a variable somewhere. (For example, I memoize the result of RSolr.connect in my Solr/Rails app.)