Bandwidth speed testing

Question

Faced with the following problem:

I need to determine bandwidth for a given ip and depending on it my task will be done in different ways.

I've written a simple implementation

Client:

public void send(Socket socket, File file) throws IOException {

    FileInputStream inputStream = null;
    DataOutputStream outputStream = null;

    try {
        inputStream = new FileInputStream(file);
        int fileSize = (int) file.length();

        byte[] buffer = new byte[fileSize];

        outputStream = new DataOutputStream(socket.getOutputStream());

        outputStream.writeUTF(file.getName());

        int recievedBytesCount = -1;

        while ((recievedBytesCount = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, recievedBytesCount);
        }
    } catch (IOException e) {
        System.out.println(e);
    } finally {
        inputStream.close();
        outputStream.close();
        socket.close();
    }

Server:

    public void recieve() throws IOException {

    ServerSocket server = new ServerSocket (port);
    Socket client = server.accept();

    DataInputStream dataInputStream = new DataInputStream(client.getInputStream());
    DataInputStream inputStream = new DataInputStream(client.getInputStream());

    String fileName = dataInputStream.readUTF();

    FileOutputStream fout = new FileOutputStream("D:/temp/" + fileName);

    byte[] buffer = new byte[65535];

    int totalLength = 0;
    int currentLength = -1;

    while((currentLength = inputStream.read(buffer)) != -1){
        totalLength += currentLength;
        fout.write(buffer, 0, currentLength);
    }
}

Test class:

public static void main(String[] args) {

        File file = new File("D:\\temp2\\absf.txt");
        Socket socket = null;
        try {
            socket = new Socket("127.0.0.1", 8080);
        } catch (IOException e) {
            e.printStackTrace();
        }

        ClientForTransfer cl = new ClientForTransfer();

        long lBegin = 0;
        long lEnd = 0;

        try {
            lBegin = System.nanoTime();
            cl.send(socket, file);
            lEnd = System.nanoTime();
        } catch (IOException e) {
            e.printStackTrace();
        }

        long lDelta = lEnd - lBegin;

        Double result =  ( file.length() / 1024.0 / 1024.0 * 8.0 / lDelta * 1e-9 );      //Mbit/s

        System.out.println(result);

    }

The problem is that using different sizes of the input files I get different speeds. Tell me, please, how to solve this problem.

please see http://stackoverflow.com/help/how-to-ask. the first thing folks may want to know is the different sizes tested and how the speed differed. — Martin Serrano, May 20 '14 at 16:22
Adding the additional tags, you can now see a number of related questions which can be quite good reading. One that caught my eye was: [Measuring Internal Network Speed/Bandwidth in Java](http://stackoverflow.com/q/3379094/289086) — , May 20 '14 at 16:47

score 1 · Accepted Answer · answered May 20 '14 at 16:10

1

The problem is the TCP slow-start. http://en.wikipedia.org/wiki/Slow-start

Try to first transfer something like 10KBs, followed by the real measurement transfer. Make sure to use the same connection for both transfers.

answered May 20 '14 at 16:10

ruediste

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score 0 · Answer 2 · answered May 20 '14 at 16:12

This is not an easily "solved" problem. It is completely normal to get different speeds for different size files, as the "bandwidth" depends on many, many factors, including raw connection speed, quality (dropped packets) and latency, and can vary even from moment to moment.

You need to try several different file sizes, starting with small files and moving to larger files until the transfer takes 10-20 seconds in order to judge average bandwidth.

Bandwidth speed testing

2 Answers2