Weird occurance in java.io.DataInputStream.read()

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class ByteTransmissionTest {
    static int LENGTH = 1000000;
    public static void main(String[] args) throws IOException {
        startServer();
        startClient();
    }

    public static void startServer() throws IOException {
        ServerSocket server = new ServerSocket(12345);
        new Thread(() -> {
            try {
                Socket client = server.accept();
                DataInputStream input = new DataInputStream(client.getInputStream());
                DataOutputStream output = new DataOutputStream(client.getOutputStream());
                byte[] bytes = new byte[LENGTH];
                output.write(bytes);
                System.out.println("Read length " + input.readUTF()); //only the first few thousand bytes!!
            }catch (IOException ex){
                throw new RuntimeException(ex);
            }
        }).start();
    }

    public static void startClient() throws IOException {
        Socket socket = new Socket("localhost", 12345);
        DataInputStream input = new DataInputStream(socket.getInputStream());
        DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());
        byte[] bytes = new byte[LENGTH];
        String read = String.valueOf(input.read(bytes));
        System.out.println(read);
        outputStream.writeUTF(String.valueOf(input.read(bytes)));
    }
}