close all UDP connections when the reuse is closed

reuse.go

@@ -71,7 +71,19 @@ func newReuse() *reuse {
 }
 
 func (r *reuse) gc() {
-	defer close(r.gcStopChan)
+	defer func() {
+		r.mutex.Lock()
+		for _, conn := range r.global {
+			conn.Close()
+		}
+		for _, conns := range r.unicast {
+			for _, conn := range conns {
+				conn.Close()
+			}
+		}
+		r.mutex.Unlock()
+		close(r.gcStopChan)
+	}()
 	ticker := time.NewTicker(garbageCollectInterval)
 	defer ticker.Stop()