当缓冲区大小超出默认值并且/或者在ServerBootStrap对象中选择了错误的覆盖位置（option或childOption）时，Netty似乎会降低上传/下载速度。当连接具有更大的延迟（~300ms）时，这变得更加明显
设置：
Netty客户端位于MacOS上，只有默认值。使用具有300ms DNS延迟的“网络链路调节器”。默认值：SendBuffer / ReceiveBuffer / LowWaterMark / HighWaterMark - 128KB / 128KB / 32KB / 64KB。
Netty服务器在Windows 8.1上，默认值为SendBuffer / ReceiveBuffer / LowWaterMark / HighWaterMark - 64KB / 64KB / 32KB / 64KB。
Netty 4.1.6版Final。
使用具有设置的IO图表使用wireshark测量速度：Y轴 - ＆gt; SUM（Y字段），Y字段 - ＆gt; tcp.len
设备位于本地网络上。
结果（速度值）：
服务器 - ＆gt;客户端传输（将SO_SNDBUF和水印低/高值设置为0.5 * SO_SNDBUF / SO_SNDBUF）：
Setting location\SO_SNDBUF | 64KB | 128KB | 1024KB
-----------------------------------------------------------------
option | 3.6MB/s| 3.6MB/s| 3.6MB/s
childOption | 0.2MB/s| 0.5MB/s| 3.6MB/s
客户端 - ＆gt;服务器传输（设置SO_RCVBUF）：
Setting location\SO_RCVBUF | 64KB | 128KB | 1024KB
-----------------------------------------------------------------
option | 0.2MB/s| 0.5MB/s| 3.6MB/s
childOption | 3.6MB/s| 0.4MB/s| 3.6MB/s
服务器代码：
“args”值：
“sendToClient”/“sendToServer”（隐含）用于传输方向。 覆盖类型的“option”/“childOption”。 缓冲区值为“1”/“2”/“3”。
ObjectEchoServer.java
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.SslContextBuilder;
import io.netty.handler.ssl.util.SelfSignedCertificate;
public final class ObjectEchoServer {
static final int PORT = 8007;
public static void main(String[] args) throws Exception {
int rcvBuf, sndBuf, lowWaterMark, highWaterMark;
rcvBuf = sndBuf = lowWaterMark = highWaterMark = 0;
switch (args[2]){
case "1":
rcvBuf = 64;
sndBuf = 64;
lowWaterMark = 32;
highWaterMark = 64;
break;
case "2":
rcvBuf = 128;
sndBuf = 128;
lowWaterMark = 64;
highWaterMark = 128;
break;
case "3":
rcvBuf = 1024;
sndBuf = 1024;
lowWaterMark = 512;
highWaterMark = 1024;
break;
}
EventLoopGroup bossGroup = new NioEventLoopGroup(1);
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline p = ch.pipeline();
p.addLast(
new ObjectEncoder(),
new ObjectDecoder(ClassResolvers.cacheDisabled(null)),
new ObjectEchoServerHandler(args[0]));
}
});
if(args[1].equalsIgnoreCase("childOption")) {
b.childOption(ChannelOption.SO_RCVBUF, rcvBuf * 1024);
b.childOption(ChannelOption.SO_SNDBUF, sndBuf * 1024);
b.childOption(ChannelOption.WRITE_BUFFER_WATER_MARK, new WriteBufferWaterMark(lowWaterMark * 1024, highWaterMark * 1024));
} else if(args[1].equalsIgnoreCase("option")){
b.option(ChannelOption.SO_RCVBUF, rcvBuf * 1024);
b.option(ChannelOption.SO_SNDBUF, sndBuf * 1024);
b.option(ChannelOption.WRITE_BUFFER_WATER_MARK, new WriteBufferWaterMark(lowWaterMark * 1024, highWaterMark * 1024));
}
// Bind and start to accept incoming connections.
b.bind(PORT).sync().channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
ObjectEchoServerHandler.java
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
public class ObjectEchoServerHandler extends ChannelInboundHandlerAdapter {
private Object msg;
ChannelHandlerContext ctx;
String sendToClient;
public ObjectEchoServerHandler(String sendToClient){
this.sendToClient = sendToClient;
}
@Override
public void channelActive(ChannelHandlerContext ctx){
this.ctx = ctx;
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
if(sendToClient.equalsIgnoreCase("sendToClient")) {//send a data stream to server
this.msg = msg;
ctx.writeAndFlush(msg).addListener(trafficGenerator);
} //else receive a data stream from client
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) {
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
cause.printStackTrace();
ctx.close();
}
private final ChannelFutureListener trafficGenerator = new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) {
if (future.isSuccess()) {
ctx.writeAndFlush(msg).addListener(trafficGenerator);
} else {
future.cause().printStackTrace();
future.channel().close();
}
}
};
}
客户代码：
“args”值：
“sendToClient”/“sendToServer”（隐含）用于传输方向。
ObjectEchoClient.java
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;
public final class ObjectEchoClient {
static final String HOST = System.getProperty("host", "127.0.0.1");
static final int PORT = 8007;
static final int SIZE = 256;
public static void main(String[] args) throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline p = ch.pipeline();
p.addLast(
new ObjectEncoder(),
new ObjectDecoder(ClassResolvers.cacheDisabled(null)),
new ObjectEchoClientHandler(args[0]));
System.out.println("senbuf:"+ ch.config().getSendBufferSize());
System.out.println("waterhigh:"+ ch.config().getWriteBufferWaterMark().high());
System.out.println("waterlow:"+ ch.config().getWriteBufferWaterMark().low());
System.out.println("recbuf:"+ ch.config().getReceiveBufferSize());
}
});
// Start the connection attempt.
b.connect(HOST, PORT).sync().channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}
}
ObjectEchoClientHandler.java
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import java.util.ArrayList;
import java.util.List;
public class ObjectEchoClientHandler extends ChannelInboundHandlerAdapter {
private final List<String> firstMessage;
private ChannelHandlerContext ctx;
private String sendToClient;
ObjectEchoClientHandler(String sendToClient) {
this.sendToClient = sendToClient;
firstMessage = new ArrayList<>(ObjectEchoClient.SIZE);
for (int i = 0; i < ObjectEchoClient.SIZE; i++) {
firstMessage.add(Integer.toString(i));
}
}
@Override
public void channelActive(ChannelHandlerContext ctx) {
this.ctx = ctx;
if(sendToClient.equalsIgnoreCase("sendToClient")) {//get a data stream from server
this.ctx.writeAndFlush(firstMessage);
} else {//send a stream of to server
this.ctx.writeAndFlush(firstMessage).addListener(trafficGenerator);
}
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
ctx.flush();
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) {
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
cause.printStackTrace();
ctx.close();
}
private final ChannelFutureListener trafficGenerator = new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) {
if (future.isSuccess()) {
ctx.writeAndFlush(firstMessage).addListener(trafficGenerator);
} else {
future.cause().printStackTrace();
future.channel().close();
}
}
};
}
最大的问题：
设置缓冲区的正确方法/位置是什么？我找到的信息（主要是代码示例）到处都是。
一个帖子（What is the difference between ServerBootstrap.option() and ServerBootstrap.childOption() in netty 4.x）表示ServerBootStrap.childOption应该用于每个客户端信息，因此我推断两个缓冲区都应该在ServerBootStrap.childOption。
答案 0 :(得分：1)
我认为这是对的
b.option(ChannelOption.SO_RCVBUF, rcvBuf * 1024);
b.option(ChannelOption.SO_SNDBUF, sndBuf * 1024);