[Delayed Job] Runs UPDATE on read-only slave shard

[edbond]

2014-05-01 08:43:17.329 [DEBUG] PG::ReadOnlySqlTransaction: ERROR:  cannot execute UPDATE in a read-only transaction
: UPDATE "delayed_jobs" SET locked_at = '2014-05-01 12:43:17.325919', locked_by = 'delayed_job.0 host:host.net pid:24847' WHERE id IN (SELECT  id FROM "delayed_jobs"  WHERE "delayed_jobs"."queue" IN ('queue_0') AND ((run_at <= '2014-05-01 12:43:17.324622' AND (locked_at IS NULL OR locked_at < '2014-05-01 09:43:17.324663') OR locked_by = 'delayed_job.0 host:host.net pid:24847') AND failed_at IS NULL) ORDER BY priority ASC, run_at ASC LIMIT 1 FOR UPDATE) RETURNING * (pid:24847)

Should it run on master?

[edbond]

It seems delayed_job uses find_by_sql with UPDATE within:
https://github.com/collectiveidea/delayed_job_active_record/blob/master/lib/delayed/backend/active_record.rb#L64

[edbond]

Here is my hack to run reserve method on master shard

module Delayed
  module Backend
    module ActiveRecord
      class Job < ::ActiveRecord::Base
        class << self
          alias_method :reserve_without_octopus, :reserve

          def reserve(worker, max_run_time = Worker.max_run_time)
            Octopus.using(:master) do
              reserve_without_octopus(worker, max_run_time)
            end
          end
        end
      end
    end
  end
end