ServerSocket serverSocket = ...;
while (!serverSocket.isClosed()) {
    Socket client = serverSocket.accept();
    new Thread(() -> {
        InputStream input = client.inputStream();
        final OutputStream output = client.outputStream();
        while (!client.isClosed()) {
            query = readQuery(input);
            threadPool.submit(() -> {
                result = processQuery(query);
                synchronized(output) {
                    write(output, result);
                }
            });
        }
    }).start();
}