Проблемы многопоточности Java HttpClient-4.3.3

try{

        // create new httpPost request with url of his class
        HttpPost httpPost = new HttpPost( "http://192.168.1.229:8080/flightcache/flightcache" );

        // create params and add it to httpPost
        List<NameValuePair> paramList = new ArrayList<NameValuePair>();
        paramList.add( new BasicNameValuePair( "json_req", format ) );
        UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity( paramList );
        httpPost.setEntity( formEntity );

        // execute request and save response
        CloseableHttpResponse response = httpclient.execute( httpPost, context );

        HttpEntity entity = response.getEntity();
        for( Header header : response.getAllHeaders() ){
            System.out.println( header.getName() + ":" + header.getValue() );
        }
        resp = entity.getContent().available() > 0;

        response.close();
        httpclient.close();
        // return the response
    }
    catch( Exception e ){
        e.printStackTrace();
}

Я пытаюсь отправить несколько запросов HttpPost одновременно с моим сервлетом, но только один поток, выполняющий указанный выше код, получает ответ. Я проверил свой сервлет, но ответы написаны правильно. httpClient был создан следующим образом.

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

Кто-нибудь может помочь/объяснить мне, почему только один поток получает ответ?

Заранее спасибо

public static void main( String[] args ) throws Exception{
    FileUtil.init();

    PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
    cm.setMaxTotal( 200 );
    cm.setDefaultMaxPerRoute( 200 );
    CloseableHttpClient httpClient = HttpClients.custom().setConnectionManager( cm ).build();

    HTTPThread.THREAD_COUNT = 2;
    HTTPThread.start = new CountDownLatch( HTTPThread.THREAD_COUNT );

    Thread[] threads = new Thread[ HTTPThread.THREAD_COUNT ];

    for( int i = 0; i < HTTPThread.THREAD_COUNT; i++ ){
        threads[ i ] = new Thread( new HTTPThread( httpClient ) );
    }

    for( Thread thread : threads ){
        thread.start();
    }

    for( Thread thread : threads ){
        thread.join();
    }

    httpClient.close();

    System.out.println( "Average response time: " + calAverage( HTTPThread.times ) + " milliseconds." );
}

Класс HTTPThread:

public HTTPThread( CloseableHttpClient httpclient ){
    this.httpclient = httpclient;
    context = HttpClientContext.create();
}

public void run(){
    String format = randomRequest();

    start.countDown();

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

    boolean resp = false;
    long timeMillis = System.currentTimeMillis();
    try{

        // create new httpPost request with url of his class
        HttpPost httpPost = new HttpPost( "http://192.168.1.229:8080/flightcache/flightcache" );

        // create params and add it to httpPost
        List<NameValuePair> paramList = new ArrayList<NameValuePair>();
        paramList.add( new BasicNameValuePair( "json_req", format ) );
        UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity( paramList );
        httpPost.setEntity( formEntity );

        // execute request and save response
        CloseableHttpResponse response = httpclient.execute( httpPost, context );

        HttpEntity entity = response.getEntity();
        resp = entity.getContent().available() > 0;

        response.close();
        httpclient.close();
        // return the response
    }
    catch( Exception e ){
        e.printStackTrace();
    }
    long end = System.currentTimeMillis() - timeMillis;

    if( !resp ){
        System.out.println( "Response was empty." );
    }

    if( end <= 0 ){
        times.add( 1L );
    }
    else{
        times.add( end );
    }

}