From 7e156b1e62e765555dd1093b120621017cefd046 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Mon, 10 Feb 2020 19:30:53 +0100
Subject: [PATCH] Reduce scope of synchronized block introduced in
 5114588cba45179c85b0ce141e10e1e16145af51 (#10013)

Motivation:

We should keep the scope of the synchronized block as small as possible.

Modifications:

Reduce scope by copy to an array first before iterate through it

Result:

Smaller scope of synchronized
---
 .../io/netty/resolver/AddressResolverGroup.java    | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/resolver/src/main/java/io/netty/resolver/AddressResolverGroup.java b/resolver/src/main/java/io/netty/resolver/AddressResolverGroup.java
index 7020219293..6a4142e4f3 100644
--- a/resolver/src/main/java/io/netty/resolver/AddressResolverGroup.java
+++ b/resolver/src/main/java/io/netty/resolver/AddressResolverGroup.java
@@ -102,19 +102,19 @@ public abstract class AddressResolverGroup<T extends SocketAddress> implements C
     @SuppressWarnings({ "unchecked", "SuspiciousToArrayCall" })
     public void close() {
         final AddressResolver<T>[] rArray;
+        final Map.Entry<EventExecutor, GenericFutureListener<Future<Object>>>[] listeners;
+
         synchronized (resolvers) {
             rArray = (AddressResolver<T>[]) resolvers.values().toArray(new AddressResolver[0]);
             resolvers.clear();
-
-            for (final Map.Entry<EventExecutor, GenericFutureListener<Future<Object>>> entry :
-                    executorTerminationListeners.entrySet()) {
-
-                entry.getKey().terminationFuture().removeListener(entry.getValue());
-            }
-
+            listeners = executorTerminationListeners.entrySet().toArray(new Map.Entry[0]);
             executorTerminationListeners.clear();
         }
 
+        for (final Map.Entry<EventExecutor, GenericFutureListener<Future<Object>>> entry : listeners) {
+            entry.getKey().terminationFuture().removeListener(entry.getValue());
+        }
+
         for (final AddressResolver<T> r: rArray) {
             try {
                 r.close();