HTTP calls testing for concurrency issues within an API

RestConcurrencyTest.java

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;

/**
 * Tests to ensure concurrent requests to the API are processed properly. IDs
 * passed in are compared with the ID returned. If the IDs do not match, this
 * indicates a concurrency issue within the API.
 * 
 * Uses Jersey for HTTP calls.
 * 
 * @author Matthew Roberts 
 * 		matthew.bowen.roberts@gmail.com 
 * 		matthewroberts.org
 * 
 */
public class RestConcurrencyTest {

	private static final String[] IDS = { "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21" };
	private static final CountDownLatch countDownLatch = new CountDownLatch(IDS.length);
	private static final String API_ENDPOINT = "http://localhost:8080/api/";
	private static final String USERNAME = "user";
	private static final String PASSWORD = "pass";

    private static Map<String, String> results = new HashMap<String, String>();

	public static void main(String[] args) {

		/*
		for (int i = 0; i < IDS.length; i++) { 
			runSegmentedRequests(IDS[i]);
		}
		 */

		ExecutorService executorService = Executors.newFixedThreadPool(IDS.length);

		for (int i = 0; i < IDS.length; i++) {

			Runnable workerThread = new ApiThread(IDS[i]);
			executorService.execute(workerThread);
		}

		try {
			countDownLatch.await();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}

		executorService.shutdown();

		System.out.println();

		String completeMatch = "SUCCESS";

		for (String key : results.keySet()) {

			if (!key.equals(results.get(key))) {
				System.out.println(key + " != " + results.get(key));
				completeMatch = "FAILURE";
			}
		}

		System.out.println(completeMatch);
	}

	private static void runSegmentedRequests(String id) {

		System.out.println("STARTING " + Thread.currentThread().getName() + " for ID " + id);
		try {

			Client client = Client.create();
			client.addFilter(new com.sun.jersey.api.client.filter.HTTPBasicAuthFilter(USERNAME,	PASSWORD));
			WebResource webResource = client.resource(API_ENDPOINT + id);
			ClientResponse response = webResource.type("application/json")
					.get(ClientResponse.class);

			if (response.getStatus() != 200) {
				throw new RuntimeException("Failed : HTTP error code : "
						+ response.getStatus() + " " + response.toString());
			}

			String output = response.getEntity(String.class);
			results.put(id, output.substring(8, 15));

		} catch (Exception e) {

			e.printStackTrace();

		}
		System.out.println("FINISHING " + Thread.currentThread().getName() + " for ID " + id);
	}

	private static class ApiThread implements Runnable {

		private String id;

		public ApiThread(String id) {

			this.id = id;
		}

		@Override
		public void run() {

			System.out.println("STARTING " + Thread.currentThread().getName() + " for ID " + id);
			getResponse(id);
			System.out.println("FINISHING " + Thread.currentThread().getName() + " for ID " + id);
			countDownLatch.countDown();
		}

		private static void getResponse(String id) {

			Client client = Client.create();
			client.addFilter(new com.sun.jersey.api.client.filter.HTTPBasicAuthFilter(USERNAME,	PASSWORD));
			WebResource webResource = client.resource(API_ENDPOINT + id);
			ClientResponse response = webResource.type("application/json").get(ClientResponse.class);

			if (response.getStatus() != 200) {
				throw new RuntimeException("Failed : HTTP error code : "
						+ response.getStatus() + " " + response.toString());
			}

			String output = response.getEntity(String.class);
			results.put(id, output.substring(8, 15));
		}
	}
}