java.net.ConnectException: Connection refused: connect during regression

[Anubhav Anand]

Hi Fellas,

My application has a number of HTTP web services. While writing a regression test I am getting "java.net.ConnectException: Connection refused: connect" exception.
Though I have verified that the service never goes down even when these errors come. The test class is attached for reference.
Please suggest what is not working out here.

public class CachePerfTest implements Runnable
{
	private static final ExecutorService es = Executors.newFixedThreadPool(100);

	private static final String[] urls = new String[] { "http://localhost:7001/MyHttpService?myParam=VAL1",
			"http://myHost:7001/MyHttpService?myParam=VAL2", "http://myHost:7001/MyHttpService?myParam=VAL3",
			"http://myHost:7001/MyHttpService?myParam=VAL4", "http://myHost:7001/MyHttpService?myParam=VAL5",
			"http://myHost:7001/MyHttpService?myParam=VAL6", "http://myHost:7001/MyHttpService?myParam=VAL7",
			"http://myHost:7001/MyHttpService?myParam=VAL8", "http://myHost:7001/MyHttpService?myParam=VAL9",
			"http://myHost:7001/MyHttpService?myParam=VAL10" };

	private static Random rand = new Random();

	public static void main(String[] args)
	{
		CachePerfTest test = null;
		System.out.println(new Date(System.currentTimeMillis()));
                List<Future<?>> results = new ArrayList<Future<?>>();

		for (int count = 0; count < 5000; count++)
		{
			test = new CachePerfTest();
			results.add(es.submit(test));
		}

		for (Future<?> f : results)
		{
			try
			{
				f.get();
			}
			catch (Exception e)
			{
				System.out.println("FUTURE ERROR : " + e.getMessage());
			}
		}

		System.out.println(new Date(System.currentTimeMillis()));
		es.shutdown();
	}

	@Override
	public void run()
	{
		try
		{
			read(urls[rand.nextInt(9)]);
			System.out.println("WORKED FINE");
		}
		catch (IOException e)
		{
			System.out.println("RUN ERROR : " + e.getMessage());
		}
	}

	private static String read(String urlStr) throws IOException
	{
		String value = null;
		StringBuilder inputLine = new StringBuilder();
		BufferedReader in = bufferedReader(urlStr);
		while ((value = in.readLine()) != null)
			inputLine.append(value);
		in.close();
		return inputLine.toString().trim();
	}

	private static BufferedReader bufferedReader(String urlStr) throws IOException
	{
		URL url = new URL(urlStr);
		return new BufferedReader(new InputStreamReader(url.openStream()));
	}
}

Thanks in advance.


<<updated code as per Rob's suggestions>>

[Rob Spoor]

The first array element uses port 2001, the others use 7001. Maybe that's the problem?

Also, your time measurement only measures how long it takes to submit all these requests. The requests themselves are executed in different threads. Store the results of the calls to es.submit() into a List<Future<?>>, then after the submitting of all requests loop over this List and call get() on each element.

[Anubhav Anand]

Thanks Rob. The port probably got incorrect while changing the URL's to dummy
Thanks for the time evaluation tip.
Though the real problem that's happening is that, when i run the program a large number of requests fail with the java.net.ConnectException: Connection refused: connect

Thanks,
Anubhav

[Anubhav Anand]

Sample console output for the program is as below, so the service is becoing unavailable for intermittent requests.

WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
RUN ERROR : Connection refused: connect
WORKED FINE
RUN ERROR : Connection refused: connect
WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE
WORKED FINE

Thanks,
Anubhav

[Rob Spoor]

I suggest you change the run method slightly to also print out which URLs are giving problems:

	@Override
	public void run()
	{
		String url = urls[rand.nextInt(9)];
		try
		{
			read(url);
			System.out.println("WORKED FINE: " + url);
		}
		catch (IOException e)
		{
			System.out.println("RUN ERROR : " + e.getMessage() + " - " + url);
		}
	}

Perhaps you'll notice a pattern.

[Anubhav Anand]

I included the url in the error, but couldn't see a pattern, as the url calls are randomized, so randomly they fail.
Though i found this link, and when i ran with requests less than 3900, the program worked
correctly for most times in windows.

Thanks,
Anubhav