clientv3: do not mark stale endpoints as unhealthy

clientv3/health_balancer.go

@@ -143,13 +143,6 @@ func (hb *healthBalancer) updateUnhealthy(timeout time.Duration) {
 		case <-time.After(timeout):
 			hb.mu.Lock()
 			for k, v := range hb.unhealthy {
-				if _, ok := hb.hostPort2ep[k]; !ok {
-					delete(hb.unhealthy, k)
-					if logger.V(4) {
-						logger.Infof("clientv3/health-balancer: removes stale host:port %q from unhealthy", k)
-					}
-					continue
-				}
 				if time.Since(v) > timeout {
 					delete(hb.unhealthy, k)
 					if logger.V(4) {
@@ -187,11 +180,13 @@ func (hb *healthBalancer) liveAddrs() []grpc.Address {
 
 func (hb *healthBalancer) hostPortError(hostPort string, err error) {
 	hb.mu.Lock()
-	hb.unhealthy[hostPort] = time.Now()
-	hb.mu.Unlock()
-	if logger.V(4) {
-		logger.Infof("clientv3/health-balancer: marking %q as unhealthy (%q)", hostPort, err.Error())
+	if _, ok := hb.hostPort2ep[hostPort]; ok {
+		hb.unhealthy[hostPort] = time.Now()
+		if logger.V(4) {
+			logger.Infof("clientv3/health-balancer: marking %q as unhealthy (%q)", hostPort, err.Error())
+		}
 	}
+	hb.mu.Unlock()
 }
 
 func (hb *healthBalancer) mayPin(addr grpc.Address) bool {