[ERROR] Failed to start server: java.net.BindException: Address already in use: bind
[ERROR] Port 25565 is already in use by another process

netstat -ano | findstr "25565"

TCP    0.0.0.0:25565          0.0.0.0:0              LISTENING       1234

taskkill /PID 1234 /F

sudo lsof -i :25565

COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
java    12345 user   23u  IPv6  12345      0t0  TCP *:25565 (LISTEN)

sudo kill -9 12345

server-port=25566

net stop lmhosts && net start lmhosts<br>
   

sudo service networking restart<br>
   

pkill -f java    # Linux/Mac上强制终止所有Java进程
taskkill /IM java.exe /F    # Windows上强制终止Java进程

@echo off
set PORT=25565

:: Check if port is in use
netstat -ano | findstr "%PORT%" > nul && (
    echo Port %PORT% is in use, killing process...
    for /f "tokens=5" %%a in ('netstat -ano ^| findstr "%PORT%"') do taskkill /PID %%a /F
    timeout /t 5 > nul
)

:: Start server
java -Xmx1024M -Xms1024M -jar mcpserver.jar nogui
pause

#!/bin/bash
PORT=25565

# Check if port is in use and kill the process if needed
if lsof -i :$PORT; then
    echo "Port $PORT is in use, killing process..."
    lsof -ti :$PORT | xargs kill -9
    sleep 5
fi

# Start server with proper memory settings (-Xmx and -Xms should match your system's available RAM)
java -Xmx1024M -Xms1024M -jar mcpserver.jar nogui || read -p "Press enter to continue"

import java.io.IOException;
import java.net.ServerSocket;

public class PortChecker {

    public static boolean isPortAvailable(int port) {
        try (ServerSocket serverSocket = new ServerSocket(port)) {
            serverSocket.setReuseAddress(true);
            return true;
        } catch (IOException e) {
            return false;
        }
    }

    public static void main(String[] args) {
        int port = 25565;
        if (!isPortAvailable(port)) { 
            System.err.println("Port " + port + " is not available");
            // Here you can implement alternative ports or exit logic

            // Example of finding next available port:
            for (int i = port + 1; i < port + 100; i++) {
                if (isPortAvailable(i)) {
                    System.out.println("Alternative available port: " + i);
                    break;
                }
            }

            System.exit(1);
        } else { 
            System.out.println("Port " + port + " is available");
        }
    }
}

public class McpServerTest {
    private McpServer server;

    @BeforeEach 
    public void setUp() throws Exception {
        int port = findAvailablePort(); // Implement this method using the PortChecker above

        server = new McpServer(port);
        server.start();
    }

    @AfterEach 
    public void tearDown() throws Exception {
        if (server != null) {
            server.stop();
        }

        // Additional cleanup if needed 
        Thread.sleep(100); // Give some time for resources to be released 
    }
}

# Find and kill the process on host machine as described above OR 

# Use a different host port mapping:
docker run -p 25566:25565 ...

docker ps -a 

docker stop container_name && docker rm container_name 

kubectl get services --all-namespaces | grep '25565'

kubectl delete pod <pod-name> --grace-period=0 --force --namespace <namespace>

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\
TcpTimedWaitDelay = dword:0000001e (30 seconds)

netsh http show urlacl | findstr "25565"
netsh http delete urlacl url=http://*:25565/

# Increase the local port range (default is usually too small for high traffic)
echo "1024 65535" > /proc/sys/net/ipv4/ip_local_port_range 

# Reduce TIME_WAIT timeout to free ports faster (default is usually too long)
echo "30" > /proc/sys/net/ipv4/tcp_fin_timeout 

# Enable reuse of TIME_WAIT sockets for new connections when safe from protocol viewpoint  
echo "1" > /proc/sys/net/ipv4/tcp_tw_reuse 

# Allow fast recycling of TIME_WAIT sockets when they're no longer needed by any connection tracking entry  
echo "1" > /proc/sys/net/ipv4/tcp_tw_recycle 

# Increase the maximum number of socket connections that can be queued for accept()
echo "4096" > /proc/sys/net/core/somaxconn  

-Dsun.net.useExclusiveBind=false // Allow multiple processes to bind to same address/port when appropriate  

-Djava.net.preferIPv4Stack=true // Prefer IPv4 over IPv6 which can sometimes cause binding issues  

-Djdk.net.useFastTcpLoopback=true // Optimize loopback connections  

<!-- In server.xml -->
<Connector port="8080" address="0.0.0.0"
           enableLookups="false"
           acceptCount="100"
           connectionTimeout="20000"
           socket.soReuseAddress="true"/>

Server server = new Server();
ServerConnector connector = new ServerConnector(server);
connector.setReuseAddress(true); // Critical setting  
connector.setPort(8080);
server.addConnector(connector);

var host = new WebHostBuilder()
    .UseKestrel(options => {
        options.ListenAnyIP(5000, listenOptions => {
            listenOptions.NoDelay = true;

            // Important for quick restart scenarios  
            listenOptions.SocketOptions = SocketOptionName.ReuseAddress;

            // For HTTPS configuration would go here  
        });
    })
    .UseStartup<Startup>()
    .Build();

host.Run();

sudo lsof -i :5353 | grep mDNSResponder  

sudo pfctl -d # Disable packet filter  
sudo pfctl -e # Re-enable after testing  

ulimit -n  

ulimit -n unlimited # For current session only  

wsl.exe --list --verbose