diff --git a/shadowsocks/lru_cache.py b/shadowsocks/lru_cache.py
index 401f19b..e67fdff 100644
--- a/shadowsocks/lru_cache.py
+++ b/shadowsocks/lru_cache.py
@@ -88,12 +88,12 @@ class LRUCache(collections.MutableMapping):
                                 self.close_callback(value)
                                 self._closed_values.add(value)
             for key in self._time_to_keys[least]:
-                self._last_visits.popleft()
                 if key in self._store:
                     if now - self._keys_to_last_time[key] > self.timeout:
                         del self._store[key]
                         del self._keys_to_last_time[key]
                         c += 1
+            self._last_visits.popleft()
             del self._time_to_keys[least]
         if c:
             self._closed_values.clear()
diff --git a/shadowsocks/udprelay.py b/shadowsocks/udprelay.py
index d3696d9..b4fcae3 100644
--- a/shadowsocks/udprelay.py
+++ b/shadowsocks/udprelay.py
@@ -1293,6 +1293,7 @@ class UDPRelay(object):
                 logging.info('closed UDP port %d', self._listen_port)
         before_sweep_size = len(self._sockets)
         self._cache.sweep()
+        self._dns_cache.sweep()
         if before_sweep_size != len(self._sockets):
             logging.debug('UDP port %5d sockets %d' % (self._listen_port, len(self._sockets)))
         self._client_fd_to_server_addr.sweep()