I have site running rails application and resque workers running in production mode, on Ubuntu 9.10, Rails 2.3.4, ruby-ee 2010.01, PostgreSQL 8.4.2
Workers constantly raised errors: PGError: server closed the connection unexpectedly.
My best guess is that master resque process establishes connection to db (e.g. authlogic does that when use User.acts_as_authentic), while loading rails app classes, and that connection becomes corrupted in fork()ed process (on exit?), so next forked children get kind of broken global ActiveRecord::Base.connection
I could reproduce very similar behaviour with this sample code imitating fork/processing in resque worker. (AFAIK, users of libpq recommended to recreate connections in forked process anyway, otherwise it’s not safe )
But, the odd thing is that when I use pgbouncer or pgpool-II instead of direct pgsql connection, such errors do not appear.
So, the question is where and how should I dig to find out why it is broken for plain connection and is working with connection pools? Or reasonable workaround?
When I created Nestor, I had the same kind of problem. The solution was to re-establish the connection in the forked process. See the relevant code at http://github.com/francois/nestor/blob/master/lib/nestor/mappers/rails/test/unit.rb#L162
From my very limited look at Resque code, I believe a call to #establish_connection should be done right about here: https://github.com/resque/resque/blob/master/lib/resque/worker.rb#L123