Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/2753#discussion_r19440361
--- Diff:
network/common/src/main/java/org/apache/spark/network/client/TransportClientFactory.java
---
@@ -0,0 +1,176 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.network.client;
+
+import java.io.Closeable;
+import java.lang.reflect.Field;
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeoutException;
+
+import io.netty.bootstrap.Bootstrap;
+import io.netty.buffer.PooledByteBufAllocator;
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelFuture;
+import io.netty.channel.ChannelInitializer;
+import io.netty.channel.ChannelOption;
+import io.netty.channel.EventLoopGroup;
+import io.netty.channel.socket.SocketChannel;
+import io.netty.util.internal.PlatformDependent;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.spark.network.TransportContext;
+import org.apache.spark.network.server.TransportClientHandler;
+import org.apache.spark.network.util.IOMode;
+import org.apache.spark.network.util.NettyUtils;
+import org.apache.spark.network.util.TransportConf;
+
+/**
+ * Factory for creating {@link TransportClient}s by using createClient.
+ *
+ * The factory maintains a connection pool to other hosts and should
return the same
+ * {@link TransportClient} for the same remote host. It also shares a
single worker thread pool for
+ * all {@link TransportClient}s.
+ */
+public class TransportClientFactory implements Closeable {
+ private final Logger logger =
LoggerFactory.getLogger(TransportClientFactory.class);
+
+ private final TransportContext context;
+ private final TransportConf conf;
+ private final ConcurrentHashMap<SocketAddress, TransportClient>
connectionPool;
+
+ private final Class<? extends Channel> socketChannelClass;
+ private final EventLoopGroup workerGroup;
+
+ public TransportClientFactory(TransportContext context) {
+ this.context = context;
+ this.conf = context.getConf();
+ this.connectionPool = new ConcurrentHashMap<SocketAddress,
TransportClient>();
+
+ IOMode ioMode = IOMode.valueOf(conf.ioMode());
+ this.socketChannelClass = NettyUtils.getClientChannelClass(ioMode);
+ this.workerGroup = NettyUtils.createEventLoop(ioMode,
conf.clientThreads(), "shuffle-client");
+ }
+
+ /**
+ * Create a new BlockFetchingClient connecting to the given remote host
/ port.
+ *
+ * This blocks until a connection is successfully established.
+ *
+ * Concurrency: This method is safe to call from multiple threads.
+ */
+ public TransportClient createClient(String remoteHost, int remotePort)
throws TimeoutException {
+ // Get connection from the connection pool first.
+ // If it is not found or not active, create a new one.
+ final InetSocketAddress address = new InetSocketAddress(remoteHost,
remotePort);
+ TransportClient cachedClient = connectionPool.get(address);
+ if (cachedClient != null && cachedClient.isActive()) {
+ return cachedClient;
+ } else if (cachedClient != null) {
+ connectionPool.remove(address, cachedClient); // Remove inactive
clients.
+ }
+
+ logger.debug("Creating new connection to " + address);
+
+ Bootstrap bootstrap = new Bootstrap();
+ bootstrap.group(workerGroup)
+ .channel(socketChannelClass)
+ // Disable Nagle's Algorithm since we don't want packets to wait
+ .option(ChannelOption.TCP_NODELAY, true)
+ .option(ChannelOption.SO_KEEPALIVE, true)
+ .option(ChannelOption.CONNECT_TIMEOUT_MILLIS,
conf.connectionTimeoutMs());
+
+ // Use pooled buffers to reduce temporary buffer allocation
+ bootstrap.option(ChannelOption.ALLOCATOR,
createPooledByteBufAllocator());
+
+ bootstrap.handler(new ChannelInitializer<SocketChannel>() {
+ @Override
+ public void initChannel(SocketChannel ch) {
+ TransportClientHandler channelHandler =
context.initializePipeline(ch);
+ TransportClient oldClient = connectionPool.putIfAbsent(address,
channelHandler.getClient());
+ if (oldClient != null) {
+ logger.debug("Two clients were created concurrently, second one
will be disposed.");
+ ch.close();
+ // Note: this type of failure is still considered a success by
Netty, and thus the
+ // ChannelFuture will complete successfully.
+ }
+ }
+ });
+
+ // Connect to the remote server
+ ChannelFuture cf = bootstrap.connect(address);
+ if (!cf.awaitUninterruptibly(conf.connectionTimeoutMs())) {
+ throw new TimeoutException(
+ String.format("Connecting to %s timed out (%s ms)", address,
conf.connectionTimeoutMs()));
+ }
+
+ TransportClient client = connectionPool.get(address);
+ if (client == null) {
+ // The only way we should be able to reach here is if the client we
created started out
+ // in the "inactive" state, and someone else simultaneously tried to
create another client to
+ // the same server. This is an error condition, as the first client
failed to connect.
+ throw new IllegalStateException("Client was unset! Must have been
immediately inactive.");
+ }
+ return client;
+ }
+
+ /** Close all connections in the connection pool, and shutdown the
worker thread pool. */
+ @Override
+ public void close() {
+ for (TransportClient client : connectionPool.values()) {
+ client.close();
--- End diff --
better to be more defensive and try catch here
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