Merge pull request #14 from fangyincheng/dubbogo-master

Add:add a log.Errorf for OnOpen

session.go

@@ -472,6 +472,7 @@ func (s *session) run() {
 	// call session opened
 	s.UpdateActive()
 	if err := s.listener.OnOpen(s); err != nil {
+		log.Errorf("[OnOpen] error: %#v", err)
 		s.Close()
 		return
 	}