/*
* 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.io.IOException;
import java.lang.reflect.Field;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicReference;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.collect.Lists;
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.TransportChannelHandler;
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
* TransportClient for the same remote host. It also shares a single worker thread pool for
* all TransportClients.
*
* TransportClients will be reused whenever possible. Prior to completing the creation of a new
* TransportClient, all given {@link TransportClientBootstrap}s will be run.
*/
public class TransportClientFactory implements Closeable {
private final Logger logger = LoggerFactory.getLogger(TransportClientFactory.class);
private final TransportContext context;
private final TransportConf conf;
private final List<TransportClientBootstrap> clientBootstraps;
private final ConcurrentHashMap<SocketAddress, TransportClient> connectionPool;
private final Class<? extends Channel> socketChannelClass;
private EventLoopGroup workerGroup;
public TransportClientFactory(
TransportContext context,
List<TransportClientBootstrap> clientBootstraps) {
this.context = Preconditions.checkNotNull(context);
this.conf = context.getConf();
this.clientBootstraps = Lists.newArrayList(Preconditions.checkNotNull(clientBootstraps));
this.connectionPool = new ConcurrentHashMap<SocketAddress, TransportClient>();
IOMode ioMode = IOMode.valueOf(conf.ioMode());
this.socketChannelClass = NettyUtils.getClientChannelClass(ioMode);
// TODO: Make thread pool name configurable.
this.workerGroup = NettyUtils.createEventLoop(ioMode, conf.clientThreads(), "shuffle-client");
}
/**
* Create a new {@link TransportClient} connecting to the given remote host / port. This will
* reuse TransportClients if they are still active and are for the same remote address. Prior
* to the creation of a new TransportClient, we will execute all {@link TransportClientBootstrap}s
* that are registered with this factory.
*
* This blocks until a connection is successfully established and fully bootstrapped.
*
* Concurrency: This method is safe to call from multiple threads.
*/
public TransportClient createClient(String remoteHost, int remotePort) throws IOException {
// 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) {
if (cachedClient.isActive()) {
logger.trace("Returning cached connection to {}: {}", address, cachedClient);
return cachedClient;
} else {
logger.info("Found inactive connection to {}, closing it.", address);
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());
final AtomicReference<TransportClient> clientRef = new AtomicReference<TransportClient>();
bootstrap.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) {
TransportChannelHandler clientHandler = context.initializePipeline(ch);
clientRef.set(clientHandler.getClient());
}
});
// Connect to the remote server
long preConnect = System.currentTimeMillis();
ChannelFuture cf = bootstrap.connect(address);
if (!cf.awaitUninterruptibly(conf.connectionTimeoutMs())) {
throw new IOException(
String.format("Connecting to %s timed out (%s ms)", address, conf.connectionTimeoutMs()));
} else if (cf.cause() != null) {
throw new IOException(String.format("Failed to connect to %s", address), cf.cause());
}
TransportClient client = clientRef.get();
assert client != null : "Channel future completed successfully with null client";
// Execute any client bootstraps synchronously before marking the Client as successful.
long preBootstrap = System.currentTimeMillis();
logger.debug("Connection to {} successful, running bootstraps...", address);
try {
for (TransportClientBootstrap clientBootstrap : clientBootstraps) {
clientBootstrap.doBootstrap(client);
}
} catch (Exception e) { // catch non-RuntimeExceptions too as bootstrap may be written in Scala
long bootstrapTime = System.currentTimeMillis() - preBootstrap;
logger.error("Exception while bootstrapping client after " + bootstrapTime + " ms", e);
client.close();
throw Throwables.propagate(e);
}
long postBootstrap = System.currentTimeMillis();
// Successful connection & bootstrap -- in the event that two threads raced to create a client,
// use the first one that was put into the connectionPool and close the one we made here.
TransportClient oldClient = connectionPool.putIfAbsent(address, client);
if (oldClient == null) {
logger.debug("Successfully created connection to {} after {} ms ({} ms spent in bootstraps)",
address, postBootstrap - preConnect, postBootstrap - preBootstrap);
return client;
} else {
logger.debug("Two clients were created concurrently after {} ms, second will be disposed.",
postBootstrap - preConnect);
client.close();
return oldClient;
}
}
/** Close all connections in the connection pool, and shutdown the worker thread pool. */
@Override
public void close() {
for (TransportClient client : connectionPool.values()) {
try {
client.close();
} catch (RuntimeException e) {
logger.warn("Ignoring exception during close", e);
}
}
connectionPool.clear();
if (workerGroup != null) {
workerGroup.shutdownGracefully();
workerGroup = null;
}
}
/**
* Create a pooled ByteBuf allocator but disables the thread-local cache. Thread-local caches
* are disabled because the ByteBufs are allocated by the event loop thread, but released by the
* executor thread rather than the event loop thread. Those thread-local caches actually delay
* the recycling of buffers, leading to larger memory usage.
*/
private PooledByteBufAllocator createPooledByteBufAllocator() {
return new PooledByteBufAllocator(
conf.preferDirectBufs() && PlatformDependent.directBufferPreferred(),
getPrivateStaticField("DEFAULT_NUM_HEAP_ARENA"),
getPrivateStaticField("DEFAULT_NUM_DIRECT_ARENA"),
getPrivateStaticField("DEFAULT_PAGE_SIZE"),
getPrivateStaticField("DEFAULT_MAX_ORDER"),
0, // tinyCacheSize
0, // smallCacheSize
0 // normalCacheSize
);
}
/** Used to get defaults from Netty's private static fields. */
private int getPrivateStaticField(String name) {
try {
Field f = PooledByteBufAllocator.DEFAULT.getClass().getDeclaredField(name);
f.setAccessible(true);
return f.getInt(null);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}