netty002读netty进阶之路之------优雅的关闭jvm的2种方式

 

1. 案例说明，以下代码会立即执行结束即jvm退出

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.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 class EchoExitServer1 {

    public static void main(String[] args) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 100)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline p = ch.pipeline();
                            p.addLast(new LoggingHandler(LogLevel.INFO));
                        }
                    });
            b.bind(18080).sync();//用同步方式绑定服务端监听端口，只有绑定不成功时阻塞
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

2. 此代码优化一点点

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.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

import java.util.logging.Logger;
public class EchoExitServer2 {

    static Logger logger = Logger.getLogger(EchoExitServer2.class.getName());
    public static void main(String[] args) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 100)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline p = ch.pipeline();
                            p.addLast(new LoggingHandler(LogLevel.INFO));
                        }
                    });
            ChannelFuture f = b.bind(18080).sync();
            f.channel().closeFuture().addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture future) throws Exception {
                    //业务逻辑处理代码，此处省略...
                    logger.info(future.channel().toString() + " 链路关闭");
                }
            });
        } finally {
//            bossGroup.shutdownGracefully();
//            workerGroup.shutdownGracefully();
        }
    }
}

3. 使用 f.channel().closeFuture().sync(); //此处会阻塞main线程继续执行

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.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

import java.util.logging.Logger;
public class EchoExitServer3 {

    static Logger logger = Logger.getLogger(EchoExitServer3.class.getName());
    public static void main(String[] args) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 100)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline p = ch.pipeline();
                            p.addLast(new LoggingHandler(LogLevel.INFO));
                        }
                    });
            ChannelFuture f = b.bind(18080).sync();
            f.channel().closeFuture().sync(); //此处会阻塞main线程继续执行
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

4. 再优化一点点

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.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

import java.util.logging.Logger;
public class EchoExitServer4 {

    static Logger logger = Logger.getLogger(EchoExitServer4.class.getName());
    public static void main(String[] args) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 100)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline p = ch.pipeline();
                            p.addLast(new LoggingHandler(LogLevel.INFO));
                        }
                    });
            ChannelFuture f = b.bind(18080).sync();
            f.channel().closeFuture().addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture future) throws Exception {
                    //业务逻辑处理代码，此处省略...
                    bossGroup.shutdownGracefully();
                    workerGroup.shutdownGracefully();
                    logger.info(future.channel().toString() + " 链路关闭");
                }
            });
        } finally {
//            bossGroup.shutdownGracefully();
//            workerGroup.shutdownGracefully();
        }
    }
}

5.  通过注册jvm退出钩子函数，进行处理退出前的逻辑Runtime.getRuntime().addShutdownHook(）；

import java.util.concurrent.TimeUnit;
public class Shutdown1 {

    public static void main(String [] args) throws Exception
    {
        Runtime.getRuntime().addShutdownHook(new java.lang.Thread(()->
        {
            //3.此代码jvm退出之前会自动调用即执行System.exit(0)完调用下面语句
            System.out.println(System.currentTimeMillis());
            System.out.println("ShutdownHook execute start...");
            System.out.println("Netty NioEventLoopGroup shutdownGracefully...");
            try {
                TimeUnit.SECONDS.sleep(10);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("ShutdownHook execute end...");
        },""));
        //1 先执行
        System.out.println(System.currentTimeMillis()  + "before");
        TimeUnit.SECONDS.sleep(7);
        System.out.println(System.currentTimeMillis());
        //2. 执行此句，但没有真正的退出
        System.exit(0);
        //此句永远不会被执行
        System.out.println("hello");
    }
}

6. 通过linux 的kill -9 pid 或windows的tctrl + c来调用如下代码关闭

import sun.misc.Signal;
import sun.misc.SignalHandler;

import java.util.concurrent.TimeUnit;

public class SignalHandlerTest {

    public static void main(String [] args) throws Exception
    {
        String signal = System.getProperties().getProperty("os.name").toLowerCase().startsWith("win") ? "INT" : "TERM";
        System.out.println(System.getProperties().getProperty("os.name").toLowerCase());
        Signal sig = new Signal("INT");//以windows操作系统为例
        Signal.handle(sig, (s)->{
//执行kill -9 pid 或windows的tctrl + c后执行如下代码
            System.out.println("Signal handle start...");
            try {
//            TimeUnit.SECONDS.sleep(Integer.MAX_VALUE);  //如果阻塞后，后面钩子函数不会执行
            TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        });
        Runtime.getRuntime().addShutdownHook(new Thread(()->
        {
            System.out.println("ShutdownHook execute start...");
            System.out.println("Netty NioEventLoopGroup shutdownGracefully...");
            try {
                TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("ShutdownHook execute end...");
        },""));
        new Thread(new Runnable() {
            public void run() {
                try {
                    TimeUnit.DAYS.sleep(Long.MAX_VALUE);
                } catch (InterruptedException e) {
                    e.printStackTrace();}}
        }, "Daemon-T").start();
    }
}