       @errors = []
 
     @handler task..., (err, res) =>
-      finish_time  = Date.now()
-      process_time = finish_time - start_time
+
       if err
 
         # Keep the error message for further inspection.

            # track tasks take the longest time processing in
            # `longest:task_name` sorted set.
            if not err
              @redis.hincrby @key('STATISTICS'), 'finished', 1
              @redis.hincrby @key('STATISTICS'), 'total_pending_time', start_time - @queued_time
              @redis.hincrby @key('STATISTICS'), 'total_processing_time', process_time


        retry = => setTimeout (=> @process task), @retry_delay

        # Different error handling strategies:
        #
        #   + `block`: block the group immediately.
        #   + `block-after-retry`: retry n times, block the group if still
