No need to defensively work jobs in another thread

activesupport/lib/active_support/queueing.rb

@@ -110,7 +110,7 @@ module ActiveSupport
     end
 
     def drain
-      Thread.new { run(@queue.pop) until @queue.empty? }.join
+      run(@queue.pop) until @queue.empty?
     end
 
     def consume

activesupport/test/queueing/test_queue_test.rb

@@ -97,6 +97,6 @@ class TestQueueTest < ActiveSupport::TestCase
 
     assert @queue.empty?
     assert job.ran?, "The job runs synchronously when the queue is drained"
-    assert_not_equal job.thread_id, Thread.current.object_id
+    assert_equal job.thread_id, Thread.current.object_id
   end
 end