BindException : "Address already in use" - when restarting server socket after stop

[Priyanka Perera]

Hi all,

Below scenario when repeated in a loop produced  "Address already in use' exception.

• Start server
• Sync start
  
• Stop
  
• Sync stop
  

Is it not guaranteed to release the server port even when the server socket is deactivated ?

netty 4.1.41.Final on openjdk-11.0.3

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

import java.net.InetSocketAddress;

public class NettySequencingServer {
    private final int port;

    public NettySequencingServer(int port) {
        this.port = port;
    }

    public static void main(String[] args) throws Exception {
        int port = 5000;
        NettySequencingServer nettySequencingServer = new NettySequencingServer(port);

        for (int i = 0; i < 10000; i++) {
            nettySequencingServer.startStop();
        }
    }

    public void startStop() throws Exception {
        final Decoder decoder = new Decoder();
        EventLoopGroup group = new NioEventLoopGroup(1);
        ServerBootstrap b = new ServerBootstrap();

        b.group(group)
                .channel(NioServerSocketChannel.class)
                .localAddress(new InetSocketAddress(port))
                .childHandler(new ChannelInitializer<SocketChannel>(){
                    @Override
                    public void initChannel(SocketChannel ch) {
                        ch.pipeline().addLast(decoder);
                    }
                });

        try {
            ChannelFuture startFuture = b.bind();
            Channel channel = startFuture.channel();
            // Start Server
            startFuture.sync();
            if (!startFuture.isSuccess()) {
                System.out.println("Start failed");
            }

            // Stop Server
            ChannelFuture stopFuture = channel.disconnect().sync();

            if (!stopFuture.isSuccess()) {
                System.out.println("Stop failed");
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
            for (StackTraceElement ele : e.getStackTrace()) {
                System.out.println(ele.toString());
            }
        }
    }
}

Address already in use
java.base/sun.nio.ch.Net.bind0(Native Method)
java.base/sun.nio.ch.Net.bind(Net.java:461)
java.base/sun.nio.ch.Net.bind(Net.java:453)
java.base/sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:227)
io.netty.channel.socket.nio.NioServerSocketChannel.doBind(NioServerSocketChannel.java:132)
io.netty.channel.AbstractChannel$AbstractUnsafe.bind(AbstractChannel.java:551)
io.netty.channel.DefaultChannelPipeline$HeadContext.bind(DefaultChannelPipeline.java:1346)
io.netty.channel.AbstractChannelHandlerContext.invokeBind(AbstractChannelHandlerContext.java:503)
io.netty.channel.AbstractChannelHandlerContext.bind(AbstractChannelHandlerContext.java:488)
io.netty.channel.DefaultChannelPipeline.bind(DefaultChannelPipeline.java:985)
io.netty.channel.AbstractChannel.bind(AbstractChannel.java:247)
io.netty.bootstrap.AbstractBootstrap$2.run(AbstractBootstrap.java:344)
io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:510)
io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:518)
io.netty.util.concurrent.SingleThreadEventExecutor$6.run(SingleThreadEventExecutor.java:1044)
io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
java.base/java.lang.Thread.run(Thread.java:834)

[Julian Feinauer]

Hi,

 

if I remember correctly you also have to free the EventLoopGroup to release all ressources completely.

Could you try that?

 

Best

Julian

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