Question

I’m trying to test a SOCKS proxy that’s under load from multiple machines. The outline of my code is something along the lines of

1. Connect directly to the server with one client, download the test file, and record the time it took.
2. Connect through the proxy with one client, download the test file, and record the time it took.
3. Connect through the proxy with multiple clients, download the test file, record the time.

1 and 2 are performed in the same function.

private static void baseline() {
    Download withProxy = new Download(socksPort, targetFile);
    Download withoutProxy = new Download(true, socksPort, targetFile); //The true argument just indicates not to use the proxy.


    try { //Come to think of it, I could just call run() directly here since this part is meant to be done serially.
        withProxy.start();
        withProxy.join();
        withoutProxy.start();
        withoutProxy.join();
                    //Some code for getting the times goes here.
    } catch (Exception e) {
        System.out.println("Couldn't get baseline.");
        e.printStackTrace();
    }
}

The download object inherits from Thread. Most of the work is done in the run() method, which looks like this:

public void run() {
    try {
        URL url = new URL("http://" + targetFile); 
        URLConnection urconn = null;
        if (baseline) {
            urconn = url.openConnection(Proxy.NO_PROXY); 
        } else {
            Proxy proxy = new Proxy(Proxy.Type.SOCKS, proxyAddr);
            urconn = url.openConnection(proxy); 
        }
        InputStreamReader isr = new InputStreamReader(urconn.getInputStream());
        System.out.println("Thread " + id + " is downloading.");
        long startTime = System.currentTimeMillis();
        char[] buf = new char[64];
        while (isr.read(buf) != -1) {
            ;
        }   
        long endTime = System.currentTimeMillis();
        isr.close();
        System.out.println("Thread " + id + " has completed.");
        delta = (endTime - startTime);

    } catch (Exception e) {
        e.printStackTrace();
        System.exit(1);
    }
}

The problem is that when I call the baseline function, it always uses the first choice of proxy – if I run the withproxy thread first, the withoutproxy thread will use the proxy. If I run withoutproxy first, withproxy ignores the proxy. The really odd thing is that later on when I try to connect through the proxy with multiple clients, it doesn’t matter how the baseline connections worked – if the baseline connection didn’t use a proxy, the multiple client connections still do.

What am I missing here?

Thanks

Answer 1

I managed to fix it – For whatever reason, the time between subsequent calls to url.openconnection() makes a difference. Calling Thread.sleep(10000) between each start() works.