Java socket server lags behind two clients

I'm a newcomer lol to stackoverflow, but I've always relied on this website I have a question about the java socket server I created When connecting (client and server), my application creates a thread for the client This is an MMORPG game server... At least I've tried There's a player who won't fall behind so badly However, there are two, it starts to show some lag

If I send spam left and right – left and right – on one client and move normally with the other client, the other will feel bad I hope to get some assistants because I've spent a week and a half struggling =) it's time for me to ask for help

The code is simple:

public static void main(String[] args) throws IOException{
    serverRooms.put(roomNumber,new Room());

    try {
        System.out.println("Starting Server...");
        serverSocket = new ServerSocket(9595,20);

        System.out.println("Server Started");
        while(run){
            Socket socket = serverSocket.accept();      // Check if we have a connection,otherwise wait

            Player player = new Player(playerCount++,socket,roomNumber);
            new Thread(player).start();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

That's how it all starts! On the player object, it looks like:

public void run() {
    while(playerIsConnected) {
        try {
            int msgid = input.readUnsignedByte();
            messageHandler(this,msgid);

        } catch (IOException e) {
            System.err.println("Player have signed off");
            playerIsConnected = false;
        }
    }

    // If Player leaves,close socket,and end thread
    try {
        socket.close();
    } catch (IOException e) {
        System.out.println("We got an error while closing a socket on player " + pid + ".");
    }
}

Messagehandler happens to be a static method of the final static class It is a global method that can be called by each thread (can this be the reason for the lag?)

public final class MessageControl {

public static void messageHandler(Player player,int msgid) throws IOException{
    DataInputStream input = player.getInputStream();
    switch (msgid) {
        case 10:
            byte hspd = (byte) Math.signum(input.readByte());
            byte vspd = (byte) Math.signum(input.readByte());
            byte dir = input.readByte();

            updatePlayerPosition(player);
            byte spd = (byte) (hspd != 0 && vspd != 0 ? player.spd-1 : player.spd);

            // Prepare packet and send to clients
            ByteBuffer buffer = ByteBuffer.allocate(11);
            buffer.put((byte) 10);
            buffer.put(shortToByte_U16(player.pid));
            buffer.put(shortToByte_U16(player.x));
            buffer.put(shortToByte_U16(player.y));
            buffer.put((byte)(hspd*spd));
            buffer.put((byte)(vspd*spd));
            buffer.put((byte)(dir));
            sendPacketToAllClients(player,buffer,true);

            // Update Player info
            player.hspd = (byte) hspd;
            player.vspd = (byte) vspd;
            player.dir = dir;
            player.lastUpdate = System.currentTimeMillis();
        break;
    }
private static void sendPacketToAllClients(Player player,ByteBuffer buffer,boolean includeMe){
    for (Player otherPlayer : player.room.getPlayersInRoom()){
        if (otherPlayer.pid != player.pid || includeMe){
            sendPacketToClient(otherPlayer,buffer);
        }
    }
}
}

About shorttobyte_ U16 (), I just created a simple method to short the cone to bytes (send buffer packets to the client through bytes) For example, I have about five such conversions, including conversion to unsigned U16

public static byte[] shortToByte_16(int x){
    short s = (short) x;
    byte[] ret = new byte[2];
    ret[0] = (byte)(s & 0xff);
    ret[1] = (byte)((s >> 8) & 0xff);
    return ret;
}

Look at the structure below, why would I fall behind any ideas?

Editor: I think I can improve it by setting settcpnodedelay to true When I spam left / right at my end, there still seems to be a lag... Other players on my screen seem very uncomfortable

Socket socket = serverSocket.accept();      // Check if we have a connection,otherwise wait
            socket.setTcpNoDelay(true);  // This helped a lot!!!
            Player player = new Player(playerCount++,roomNumber);
            new Thread(player).start();

From what I see... My "spam left / right" end seems to lack packets sent by the server

Solution

Problem solved. =) Settcpnodedelay true did a trick About the part I said I lost the packet, I actually didn't The two messages are combined and passed in as one message My program only reads the first few bytes and ignores the rest You have to put a byte in front to indicate the size of the message Once in place, I set up a while loop to read it until it can no longer read. (=) Thank you for helping me My first article, this is a grand experience