From 4cacdb888b49fd309fd5d67689985dc772478e38 Mon Sep 17 00:00:00 2001
From: guhanjie <guhanjiehao@163.com>
Date: Fri, 21 Jul 2023 11:03:27 +0800
Subject: [PATCH] Reduce dns lookup overhead on NodeScheduler

It does not need to dns lookup for hostname if HostAddress has port, which incurred additional overhead when dns too slow on some host environment.
---
 .../execution/scheduler/NodeScheduler.java    | 36 +++++++++----------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/core/trino-main/src/main/java/io/trino/execution/scheduler/NodeScheduler.java b/core/trino-main/src/main/java/io/trino/execution/scheduler/NodeScheduler.java
index 0536db2c1e43..fef4831353c4 100644
--- a/core/trino-main/src/main/java/io/trino/execution/scheduler/NodeScheduler.java
+++ b/core/trino-main/src/main/java/io/trino/execution/scheduler/NodeScheduler.java
@@ -107,17 +107,17 @@ public static List<InternalNode> selectExactNodes(NodeMap nodeMap, List<HostAddr
                     .filter(node -> includeCoordinator || !coordinatorIds.contains(node.getNodeIdentifier()))
                     .forEach(chosen::add);
 
-            InetAddress address;
-            try {
-                address = host.toInetAddress();
-            }
-            catch (UnknownHostException e) {
-                // skip hosts that don't resolve
-                continue;
-            }
-
             // consider a split with a host without a port as being accessible by all nodes in that host
             if (!host.hasPort()) {
+                InetAddress address;
+                try {
+                    address = host.toInetAddress();
+                }
+                catch (UnknownHostException e) {
+                    // skip hosts that don't resolve
+                    continue;
+                }
+
                 nodeMap.getNodesByHost().get(address).stream()
                         .filter(node -> includeCoordinator || !coordinatorIds.contains(node.getNodeIdentifier()))
                         .forEach(chosen::add);
@@ -133,17 +133,17 @@ public static List<InternalNode> selectExactNodes(NodeMap nodeMap, List<HostAddr
 
                 chosen.addAll(nodeMap.getNodesByHostAndPort().get(host));
 
-                InetAddress address;
-                try {
-                    address = host.toInetAddress();
-                }
-                catch (UnknownHostException e) {
-                    // skip hosts that don't resolve
-                    continue;
-                }
-
                 // consider a split with a host without a port as being accessible by all nodes in that host
                 if (!host.hasPort()) {
+                    InetAddress address;
+                    try {
+                        address = host.toInetAddress();
+                    }
+                    catch (UnknownHostException e) {
+                        // skip hosts that don't resolve
+                        continue;
+                    }
+
                     chosen.addAll(nodeMap.getNodesByHost().get(address));
                 }
             }