java httpclient 4.x performance guide to resolve issue

Question

There was nice article http://hc.apache.org/httpclient-3.x/performance.html related to http performance, pooling, e.t.c. Can't find the same for the latest 4.x version. Did anyone see it? I met perf issues under heavy load and would like to resolve them. I'm using 4.1 version. Here is profiler output:

26% org.apache.http.impl.client.CloseableHttpClient.execute(multiple parameter matches) :26,107,40
26% org.apache.http.impl.client.CloseableHttpClient.execute(org.apache.http.client.methods.HttpUriRequest, org.apache.http.protocol.HttpContext) :82,46
26% org.apache.http.impl.client.AbstractHttpClient.doExecute(org.apache.http.HttpHost, org.apache.http.HttpRequest, org.apache.http.protocol.HttpContext) :882,818
26% org.apache.http.impl.client.AbstractHttpClient.createHttpContext() :301
26% org.apache.http.impl.client.AbstractHttpClient.getConnectionManager() :484
26% org.apache.http.impl.client.AbstractHttpClient.createClientConnectionManager() :321
26% org.apache.http.impl.conn.SchemeRegistryFactory.createDefault() :52
26% org.apache.http.conn.ssl.SSLSocketFactory.getSocketFactory() :168
26% org.apache.http.conn.ssl.SSLContexts.createDefault() :58
26% javax.net.ssl.SSLContext.init(javax.net.ssl.KeyManager[], javax.net.ssl.TrustManager[], java.security.SecureRandom) :283
26% sun.security.ssl.SSLContextImpl.engineInit(javax.net.ssl.KeyManager[], javax.net.ssl.TrustManager[], java.security.SecureRandom) :83,92
26% javax.net.ssl.TrustManagerFactory.init(java.security.KeyStore) :250
26% sun.security.ssl.TrustManagerFactoryImpl.engineInit(java.security.KeyStore) :51
26% sun.security.ssl.TrustManagerFactoryImpl.getCacertsKeyStore(java.lang.String) :221
26% java.security.KeyStore.load(java.io.InputStream, char[]) :1214
26% sun.security.provider.JavaKeyStore$JKS.engineLoad(java.io.InputStream, char[]) :55
26% sun.security.provider.JavaKeyStore.engineLoad(java.io.InputStream, char[]) :723,747
26% java.security.cert.CertificateFactory.generateCertificate(java.io.InputStream) :339
26% sun.security.provider.X509Factory.engineGenerateCertificate(java.io.InputStream) :93
26% sun.security.provider.X509Factory.getFromCache(sun.security.util.Cache, byte[]) :203

I have 4 methods sending some data via HTTP using httpclient and each of these methods consume 25% of total time. The rest processing takes millis. Looks like I'm using httpclient in a wrong way.

EDIT: See oleg answers + read that https://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html answers all realated questions

Main parts are: Nice way to build pooling manager

PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
// Increase max total connection to 200
cm.setMaxTotal(200);
// Increase default max connection per route to 20
cm.setDefaultMaxPerRoute(20);
// Increase max connections for localhost:80 to 50
HttpHost localhost = new HttpHost("locahost", 80);
cm.setMaxPerRoute(new HttpRoute(localhost), 50);

CloseableHttpClient httpClient = HttpClients.custom()
        .setConnectionManager(cm)
        .build();

A way to use HttpClient concurrently

//While HttpClient instances are thread safe and can be shared
//between multiple threads of execution, it is highly recommended that 
//each thread maintains its own dedicated instance of HttpContext .


static class GetThread extends Thread {

    private final CloseableHttpClient httpClient;
    private final HttpContext context;
    private final HttpGet httpget;

    public GetThread(CloseableHttpClient httpClient, HttpGet httpget) {
        this.httpClient = httpClient;
        this.context = HttpClientContext.create();
        this.httpget = httpget;
    }

    @Override
    public void run() {
        try {
            CloseableHttpResponse response = httpClient.execute(
                    httpget, context);
            try {
                HttpEntity entity = response.getEntity();
            } finally {
                response.close();
            }
        } catch (ClientProtocolException ex) {
            // Handle protocol errors
        } catch (IOException ex) {
            // Handle I/O errors
        }
    }

}

Answer 1

The main recommendation is still the same as it was for 3.1

Please DO re-use the HttpClient instance! HttpClient instances are very expensive. By throwing it away not only you throw away the instance itself, you also throw away the SSL context, the connection manager, and all persistent connections that might be kept-alive by the connection manager.