Question

I have a background operation I would like to occur every 20 seconds in Rails given that some condition is true. It kicked off when a certain controller route is hit, and it looks like this

def startProcess
    argId = self.id
    t = Thread.new do
        while (Argument.isRunning(argId)) do
            Argument.update(argId)
            Argument.markVotes(argId)
            puts "Thread ran"
            sleep 20
        end
    end
end

However, this code does absolutely nothing to my database unless I call "t.join" in which case my whole server is blocked for a long time (but it works).

Why can’t the read commit ActiveRecords without being joined to the main thread?
The thread calls methods that look something like

def sample
  model = Model.new()
  model.save()
end

but the models are not saved to the DB unless the thread is joined to the main thread. Why is this? I have been banging my head about this for hours.

EDIT:

The answer marked correct is technically correct, however this edit is to outline the solution I eventually used. The issues is that Ruby does not have true threading, so even once I got my DB connection working the Thread couldn’t get processor time unless there was little traffic to the server.

Solution: start a new Heroku worker instance, point it at the same database, and make it execute a rake task that has the same functionality as the thread. Now everything works great.

Answer 1

You need to re-establish the database connection:

ActiveRecord::Base.establish_connection Rails.env