From fb61cc878f9f15a78eb565122cc4cf82531067d9 Mon Sep 17 00:00:00 2001
From: Hanson <huangsheng.hs@alibaba-inc.com>
Date: Tue, 22 Nov 2016 11:43:26 +0800
Subject: [PATCH] Ensure trying to recover from exceptionCaught on the
 ServerChannel works as expected

Motivation:

When "Too many open files" happens,the URLClassLoader cannot do any classloading because URLClassLoader need a FD  for findClass. Because of this the anonymous inner class that is created to re-enable auto read may cause a problem.

Modification:

Pre-create Runnable that is scheduled and so ensure it is not lazy loaded.

Result:

No more problems when try to recover.
---
 .../io/netty/bootstrap/ServerBootstrap.java   | 26 ++++++++++++-------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/transport/src/main/java/io/netty/bootstrap/ServerBootstrap.java b/transport/src/main/java/io/netty/bootstrap/ServerBootstrap.java
index 9e7eeab49f..92985bcdf1 100644
--- a/transport/src/main/java/io/netty/bootstrap/ServerBootstrap.java
+++ b/transport/src/main/java/io/netty/bootstrap/ServerBootstrap.java
@@ -176,7 +176,7 @@ public class ServerBootstrap extends AbstractBootstrap<ServerBootstrap, ServerCh
 
         p.addLast(new ChannelInitializer<Channel>() {
             @Override
-            public void initChannel(Channel ch) throws Exception {
+            public void initChannel(final Channel ch) throws Exception {
                 final ChannelPipeline pipeline = ch.pipeline();
                 ChannelHandler handler = handler();
                 if (handler != null) {
@@ -191,7 +191,7 @@ public class ServerBootstrap extends AbstractBootstrap<ServerBootstrap, ServerCh
                     @Override
                     public void run() {
                         pipeline.addLast(new ServerBootstrapAcceptor(
-                                currentChildGroup, currentChildHandler, currentChildOptions, currentChildAttrs));
+                                ch, currentChildGroup, currentChildHandler, currentChildOptions, currentChildAttrs));
                     }
                 });
             }
@@ -227,14 +227,27 @@ public class ServerBootstrap extends AbstractBootstrap<ServerBootstrap, ServerCh
         private final ChannelHandler childHandler;
         private final Entry<ChannelOption<?>, Object>[] childOptions;
         private final Entry<AttributeKey<?>, Object>[] childAttrs;
+        private final Runnable enableAutoReadTask;
 
         ServerBootstrapAcceptor(
-                EventLoopGroup childGroup, ChannelHandler childHandler,
+                final Channel channel, EventLoopGroup childGroup, ChannelHandler childHandler,
                 Entry<ChannelOption<?>, Object>[] childOptions, Entry<AttributeKey<?>, Object>[] childAttrs) {
             this.childGroup = childGroup;
             this.childHandler = childHandler;
             this.childOptions = childOptions;
             this.childAttrs = childAttrs;
+
+            // Task which is scheduled to re-enable auto-read.
+            // It's important to create this Runnable before we try to submit it as otherwise the URLClassLoader may
+            // not be able to load the class because of the file limit it already reached.
+            //
+            // See https://github.com/netty/netty/issues/1328
+            enableAutoReadTask = new Runnable() {
+                @Override
+                public void run() {
+                    channel.config().setAutoRead(true);
+                }
+            };
         }
 
         @Override
@@ -276,12 +289,7 @@ public class ServerBootstrap extends AbstractBootstrap<ServerBootstrap, ServerCh
                 // stop accept new connections for 1 second to allow the channel to recover
                 // See https://github.com/netty/netty/issues/1328
                 config.setAutoRead(false);
-                ctx.channel().eventLoop().schedule(new Runnable() {
-                    @Override
-                    public void run() {
-                       config.setAutoRead(true);
-                    }
-                }, 1, TimeUnit.SECONDS);
+                ctx.channel().eventLoop().schedule(enableAutoReadTask, 1, TimeUnit.SECONDS);
             }
             // still let the exceptionCaught event flow through the pipeline to give the user
             // a chance to do something with it