Apache async HttpClient not fast

Question

I am pretty new to Apache http client and am trying to get status code from a website. Found the following example on Apache http tutorial.

import java.util.concurrent.CountDownLatch;
import org.apache.http.HttpResponse;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.concurrent.FutureCallback;
import org.apache.http.impl.nio.client.CloseableHttpAsyncClient;
import org.apache.http.impl.nio.client.HttpAsyncClients;
public class Abc {
    static long d2;
    public static void main(final String[] args) throws Exception {
        d2=System.currentTimeMillis();
        RequestConfig requestConfig = RequestConfig.custom()
            .setSocketTimeout(3000)
            .setConnectTimeout(3000).build();
        CloseableHttpAsyncClient httpclient = HttpAsyncClients.custom()
            .setDefaultRequestConfig(requestConfig)
            .build();
        try {
            httpclient.start();
            final HttpGet[] requests = new HttpGet[] {
                    new HttpGet("http://192.168.26.175:8080/examples/eye/abc10000.jsp")
            };
            final CountDownLatch latch = new CountDownLatch(1);
            for (int v=0;v<1000;v++) {
                httpclient.execute(requests[0], new FutureCallback<HttpResponse>() {

                    public void completed(final HttpResponse response) {
                        latch.countDown();
                        System.out.println(requests[0].getRequestLine() + "->" + response.getStatusLine());
                    }

                    public void failed(final Exception ex) {
                        latch.countDown();
                        System.out.println(requests[0].getRequestLine() + "->" + ex);
                    }

                    public void cancelled() {
                        latch.countDown();
                        System.out.println(requests[0].getRequestLine() + " cancelled");
                    }

                });
            }
            latch.await();
            System.out.println("Shutting down");
        } finally {
            httpclient.close();
        }
        System.out.println("Done");
      long  d1=System.currentTimeMillis();
      System.out.println(d1-d2);
    }

}

Is it really asynchronous or are the calls made serially. What has to be done to make calls asynchronous and faster.

Answer 1

As the requests are going through the same route following changes will have to be made.

CloseableHttpAsyncClient httpclient = HttpAsyncClients.custom()
            .setDefaultRequestConfig(requestConfig)
            .setMaxConnPerRoute(1000)
            .setMaxConnTotal(1000)
            .build();

Answer 2

First and foremost: CloseableHttpAsyncClient instances are very expensive. Please do NOT create a new CloseableHttpAsyncClient for each and every request. It is like creating a new browser process for each link click, is completely wasteful and is very slow. It is strongly recommended to use the same CloseableHttpAsyncClient instance for the entire lifespan of a logical component.

Pretty much in all cases a blocking client is likely to be considerably faster than a non-blocking (NIO based) one (as long as the number of concurrent requests is below, say, 1000). Unless you are building a proxy of some sort you might be much better served by a blocking HTTP client such as Apache HttpClient.