"PG::Error: connection is closed" when enqueuing a job in a connection shared with ActiveRecord

[raul]

We're using QC 2.1.3 in a Rails 3.2.13 app, with the version 0.14.1 of the pg gem. Sometimes we get a PG::Error: connection is closed error when enqueuing jobs. Unfortunately I haven't been able to reproduce the problem in a controlled environment.

Enqueuing code:

module Approvable

  extend ActiveSupport::Concern

  included do
    # ...
    after_save :queue_approval_notification
  end

  # ...

  def queue_approval_notification
    send_email = approvable? && (just_approved? || just_unapproved?)
    QC.enqueue("#{self.class}.email_approval_notification", self.id, approved?, current_user.email) if send_email
  end

Error stacktrace:

2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic/conn.rb:81:in `finish'
2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic/conn.rb:81:in `disconnect'
2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic/conn.rb:19:in `rescue in block in execute'
2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic/conn.rb:11:in `block in execute'
2013-04-06T00:11:24+00:00 app[web.1]: <internal:prelude>:10:in `synchronize'
2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic/conn.rb:9:in `execute'
2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic/queries.rb:8:in `block in insert'
2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic.rb:78:in `log_yield'
2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic/queries.rb:6:in `insert'
2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic/queue.rb:11:in `enqueue'
2013-04-06T00:11:24+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/queue_classic-2.1.3/lib/queue_classic.rb:61:in `method_missing'
2013-04-06T00:11:24+00:00 app[web.1]: /app/app/models/approvable.rb:131:in `queue_approval_notification'

[senny]

Do you use QC_DATABASE_URL to connect to your database or do you reuse a connection for example from Active Record?

[raul]

I share Active Record´s:

require 'queue_classic'
QC::Conn.connection = ActiveRecord::Base.connection.raw_connection

[senny]

reusing the Active Record connection is not working flawlessly at the moment. You can find the discussion here #96 and here #134.

[raul]

Good call, thanks! We're using it with its own connection now, I'll update the issue if we notice it gets more stable.

[raul]

This is looking good - no issues since we stopped sharing the ActiveRecord connection.

[senny]

great! Thanks for reporting ❤️ let me close this one for now as it is not related to the QC core. I am working on a better integration with Rails so I hope to resolve this problem in the future: #134