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java - 为什么我在接受新 channel 的 Netty 服务器 Bootstrap 上看到性能下降?

转载 作者:搜寻专家 更新时间:2023-11-01 03:34:02 25 4
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我还在用 Netty 3.10。我写了一个单元测试来检查 Netty 老板线程的性能。我在单元测试主线程中使用简单的 Netty 服务器 Bootstrap ,并在缓存线程池中生成 100 个 Java sync-IO 客户端。我注意到我认为很奇怪的性能下降。每个客户端打开一个套接字,写入数据并关闭,关闭后记录持续时间(毫秒)。附上我的单元测试。我的单元测试的典型输出是,按给定的顺序:

  1. 43 x 客户完成。时长:0
  2. 26 x 客户完成。时长:16
  3. 16 x 客户完成。时长:0
  4. 3 x 客户完成。时长:517
  5. 11 x 客户完成。时长:3003
  6. 1 x 客户完成。时长:6036

所以有 1 个客户端必须等待 6 秒才能获得打开的 TCP/IP channel ,而 11 个客户端必须等待 3 秒。我还检查了时间在哪里花费/丢失。在客户端始终是 new Socket(String,int)。在服务器端,管道工厂被触发的时间已经过去了。

我的单元测试的线程模型是这个还是 Netty bootstrap/boss 的原因?

import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.charset.Charset;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicInteger;

import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelFactory;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.channel.group.ChannelGroup;
import org.jboss.netty.channel.group.DefaultChannelGroup;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
import org.junit.After;
import org.junit.Assert;
import org.junit.Test;

public class NettyServerBossTest {

private static final String SRV_HOST = "localhost";
private static final int SRV_PORT = 8080;
private static final byte[] MSG = "Hello world!".getBytes(Charset.forName("UTF-8"));
private static final int WAIT_MAX_MILLIS = 10 * 1000;

private final ChannelGroup channels = new DefaultChannelGroup();

private final int expected = 100;
private final AtomicInteger actual = new AtomicInteger();

private volatile boolean failed;
private ExecutorService clientThreads;
private Throwable cause;
private ServerBootstrap bootstrap;

@Test
public void test() {
createServer();
createClients();
awaitClients();
verifyFailure();
}

private void awaitClients() {
final long startMillis = System.currentTimeMillis();
final long maxMillis = startMillis + WAIT_MAX_MILLIS;
while ((this.actual.get() < this.expected) && !isFailed() && (System.currentTimeMillis() < maxMillis)) {
try {
Thread.sleep(250L);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("Total duration: " + (System.currentTimeMillis() - startMillis));
Assert.assertEquals(this.expected, this.actual.get());
}

private void createClients() {
this.clientThreads = Executors.newCachedThreadPool();
for (int i = 0; i < this.expected; i++) {
this.clientThreads.execute(new PlainSocketClient());
}
}

private void closeChannels() {
try {
this.channels.close().await(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}

private void createServer() {
final ExecutorService bosses = Executors.newCachedThreadPool();
final ExecutorService workers = Executors.newCachedThreadPool();
final ChannelFactory factory = new NioServerSocketChannelFactory(bosses, workers);
this.bootstrap = new ServerBootstrap(factory);
this.bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
@Override
public ChannelPipeline getPipeline() {
return Channels.pipeline(new DiscardServerHandler());
}
});
this.bootstrap.setOption("child.tcpNoDelay", Boolean.TRUE);
this.bootstrap.setOption("child.keepAlive", Boolean.TRUE);
this.bootstrap.bind(new InetSocketAddress(SRV_HOST, SRV_PORT));
}

/**
* Fail unit test
*
* @param cause
* cause of failure
*/
public synchronized void setCause(Throwable cause) {
if (!this.failed && (cause == null)) {
this.failed = true;
this.cause = cause;
}
}

@After
public void after() {
closeChannels();
if (this.clientThreads != null) {
this.clientThreads.shutdownNow();
}
if (this.bootstrap != null) {
this.bootstrap.releaseExternalResources();
}
}

/**
* Check if unit test has failed
*
* @return <code>true</code> if failed, <code>false</code> if still OK
*/
public boolean isFailed() {
return this.failed;
}

/**
* Get cause of failure
*
* @return cause or <code>null</code>
*/
public synchronized Throwable getCause() {
return this.cause;
}

/**
* Make sure test has not failed with exception
*/
public void verifyFailure() {
if (this.failed) {
throw new IllegalStateException("test failed", getCause());
}
}

public abstract class TestRunnable implements Runnable {

@Override
public final void run() {
try {
execute();
} catch (Exception e) {
handleException(e);
}
}

protected abstract void handleException(Throwable e);

protected abstract void execute() throws Exception;

}

public abstract class AsyncThreadsTestRunnable extends TestRunnable {

@Override
protected final void handleException(Throwable e) {
setCause(e);
}

}

public class PlainSocketClient extends AsyncThreadsTestRunnable {

@Override
protected void execute() throws Exception {
final long startMillis = System.currentTimeMillis();
try (Socket sock = new Socket(SRV_HOST, SRV_PORT)) {
sock.getOutputStream().write(MSG);
}
NettyServerBossTest.this.actual.incrementAndGet();
System.out.println("Client done. Duration: " + (System.currentTimeMillis() - startMillis));
}

}

public class DiscardServerHandler extends SimpleChannelHandler {

@Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
NettyServerBossTest.this.channels.add(e.getChannel());
}

@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
// discard
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
e.getCause().printStackTrace();

Channel ch = e.getChannel();
ch.close();
}
}

最佳答案

我认为你登录的时间并不都是用在打开套接字上,它是在线程切换上花费的,因为当线程A打开一个套接字时,CPU可能会切换到线程B,然后当套接字打开完成后,CPU可能不会切换到线程 A 立即执行但在执行许多其他线程之后。我已将您的 PlainSocketClient 更改为添加同步以确保减少线程切换影响:

public class PlainSocketClient extends AsyncThreadsTestRunnable {
private static final String LOCK = "LOCK";

@Override
protected void execute() throws Exception {
synchronized (LOCK) {
final long startMillis = System.currentTimeMillis();
try (Socket sock = new Socket(SRV_HOST, SRV_PORT)) {
sock.getOutputStream().write(MSG);
}
NettyServerBossTest.this.actual.incrementAndGet();
System.out.println("Client done. Duration: " + (System.currentTimeMillis() - startMillis));
}
}
}

然后他们几乎只输出0或1。你可以自己测试一下。它只是证明线程切换时的耗时,并不意味着您需要在代码中添加同步。

关于java - 为什么我在接受新 channel 的 Netty 服务器 Bootstrap 上看到性能下降?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37279769/

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