Question

I have a simple UDP server that creates a new thread for processing incoming data. While testing it by sending about 100 packets/second I notice that it’s memory usage continues to increase. Is there any leak evident from my code below?

Here is the code for the server.

public class UDPServer
{
    public static void main(String[] args)
    {
        UDPServer server = new UDPServer(15001);
        server.start();
    }

    private int port;

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

    public void start()
    {
        try
        {
            DatagramSocket ss = new DatagramSocket(this.port);

            while(true)
            {   
                byte[] data = new byte[1412];
                DatagramPacket receivePacket = new DatagramPacket(data, data.length);
                ss.receive(receivePacket);
                new DataHandler(receivePacket.getData()).start();
            }

        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

}

Here is the code for the new thread that processes the data. For now, the run() method doesn’t do anything.

public class DataHandler extends Thread
{
    private byte[] data;

    public DataHandler(byte[] data)
    {
        this.data = data;
    }

    @Override
    public void run()
    {
        System.out.println("run");
    }

}

Answer 1

Of couse, you’re allocating (at least) 1412 bytes of new memory each loop. You’ll see an increase of memory usage until GC kicks in and cleans all unused allocated data.

Use a memory profiler like Java VisualVM to visualize and analyse the behaviour.