HttpClient stop executing the same HttpGet method in a loop after executing twice

Question

Here is my Main Method:

public static void main(String[] args) {

    BasicCookieStore cookieStore = null;
    HttpResponse httpResponse = null;
    HttpClient httpClient = HttpClients.createDefault();
    while (true) {
        HttpUriRequest request = new HttpGet("http://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/impl/client/HttpClientBuilder.html");
        try {
            httpResponse = httpClient.execute(request);
            System.out.println(httpResponse.getStatusLine().getStatusCode());
        } catch (Exception e) {
            System.out.println(httpResponse.getStatusLine().getStatusCode());
            e.printStackTrace();
        }
    }
}

After executing 2 times the HttpClient stop executing the same HttpGet. While, I instantiate a new HttpClient in the loop, it won't stop. I wander if there is something strategy preventing the HttpClient from executing the same HttpGet method more than 2 times? Who can help me, I will be very grateful!

Try to consume the response entity. – kupsef Nov 11 '15 at 12:12 — kupsef, Nov 11 '15 at 12:12
problem perfectly solved ! Thanks! – zhongwei Nov 11 '15 at 12:19 — zhongwei, Nov 11 '15 at 12:19

stalet · Accepted Answer · 2019-08-19T11:31:37.760

11

The client is using a pool of connection to reach the web server. See HttpClientBuilder#build(). When creating a default httpclient and nothing is specified it creates a pool with size of 2. So after 2 is used, it waits indefinitely trying to get the third connection from the pool.

You must read the response or close the connection, in order to re-use the client object.

See updated code sample:

public static void main(String[] args) {

    BasicCookieStore cookieStore = null;
    HttpResponse httpResponse = null;
    HttpClient httpClient = HttpClients.createDefault();
    while (true) {
        HttpUriRequest request = new HttpGet("http://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/impl/client/HttpClientBuilder.html");
        try {
            httpResponse = httpClient.execute(request);
            httpResponse.getEntity().getContent().close();
            System.out.println(httpResponse.getStatusLine().getStatusCode());
        } catch (Exception e) {
            System.out.println(httpResponse.getStatusLine().getStatusCode());
            e.printStackTrace();
        }
    }
}

edited Aug 19 '19 at 11:31

answered Nov 11 '15 at 12:18

stalet

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I've got this. Thanks all the way! StackOverflow is a nice place for me – zhongwei Nov 11 '15 at 12:20
@Zavael, I‘m also wondering why this happens. It in deed executes 2 times. – zhongwei Nov 11 '15 at 12:42
2

The client is using a pool of connection to reach the web server. See HttpClientBuilder#build(). When creating a default httpclient and nothing is specified it creates a pool with size of 2. So after 2 is used, it waits indefinetly trying to get the third connection from the pool. – stalet Nov 11 '15 at 12:48
woo! You guy knows all! Thanks – zhongwei Nov 11 '15 at 13:17
@stalet thanks +1, that valuable comment would greatly enhance the answer :) – Zavael Nov 11 '15 at 14:06
1

@Zavael: Updated the answer – stalet Nov 11 '15 at 14:12
@stalet is there a way to update pool size or its best practice to close the httpClient for each call. – JayC Mar 31 '20 at 14:45
@Jesse you should definitely close the client after each call. – stalet Apr 07 '20 at 11:45

HttpClient stop executing the same HttpGet method in a loop after executing twice

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