Question

I have been trying to implement connection pool with Apache HttpClient (4.1.3) and ThreadSafeClientConnManager. And I faced with a problem when tried to set maximum connections for a route. Basically I followed examples from hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html. For example, I want to set default connections per route to 10 and for ceratin route to 5 connections.

ThreadSafeClientConnManager cm = new ThreadSafeClientConnManager(schemeRegistry);
cm.setMaxTotal(30);
cm.setDefaultMaxPerRoute(10);

HttpHost host = new HttpHost("hc.apache.org", 80, "http");
cm.setMaxForRoute(new HttpRoute(host, null, false), 5);

DefaultHttpClient httpClient = new DefaultHttpClient(cm);

And then I execute requests in threads:

  public void run() {
        try {
            HttpResponse response = this.httpClient.execute(this.httpget, this.context);
            HttpEntity entity = response.getEntity();
            if (entity != null) {
                // do something useful with the entity
            }
            // ensure the connection gets released to the manager
            EntityUtils.consume(entity);
        } catch (Exception ex) {
            this.httpget.abort();
        }
    }

And get logs like this:

DEBUG Thread-0 [org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager]: Get connection: HttpRoute[{}->http://hc.apache.org], timeout = 10000
DEBUG Thread-4 [org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager]: Get connection: HttpRoute[{}->http://hc.apache.org], timeout = 10000
DEBUG Thread-1 [org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager]: Get connection: HttpRoute[{}->http://hc.apache.org], timeout = 10000
DEBUG Thread-7 [org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager]: Get connection: HttpRoute[{}->http://hc.apache.org], timeout = 10000
DEBUG Thread-3 [org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager]: Get connection: HttpRoute[{}->http://hc.apache.org], timeout = 10000
DEBUG Thread-5 [org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager]: Get connection: HttpRoute[{}->http://hc.apache.org], timeout = 10000
DEBUG Thread-8 [org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager]: Get connection: HttpRoute[{}->http://hc.apache.org], timeout = 10000
DEBUG Thread-2 [org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager]: Get connection: HttpRoute[{}->http://hc.apache.org], timeout = 10000
DEBUG Thread-6 [org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager]: Get connection: HttpRoute[{}->http://hc.apache.org], timeout = 10000
DEBUG Thread-0 [org.apache.http.impl.conn.tsccm.ConnPoolByRoute]: [HttpRoute[{}->http://hc.apache.org]] total kept alive: 0, total issued: 0, total allocated: 0 out of 30
DEBUG Thread-0 [org.apache.http.impl.conn.tsccm.ConnPoolByRoute]: No free connections [HttpRoute[{}->http://hc.apache.org]][null]
DEBUG Thread-0 [org.apache.http.impl.conn.tsccm.ConnPoolByRoute]: Available capacity: 10 out of 10 [HttpRoute[{}->http://hc.apache.org]][null]
DEBUG Thread-0 [org.apache.http.impl.conn.tsccm.ConnPoolByRoute]: Creating new connection [HttpRoute[{}->http://hc.apache.org]]

Why did I get Available capacity: 10 out of 10 for this route, but not 5 as I specified?

Thanks

UPD: If I run this statement cm.getMaxForRoute(new HttpRoute(host, null, false)) after creating connection manager it will return 5.
But if I’ll try to check max connections for route in thread (after getting response):

HttpHost target = (HttpHost) context.getAttribute(ExecutionContext.HTTP_TARGET_HOST);
cm.getMaxForRoute(new HttpRoute(target));

Connection manager will return the same thing that in logs (10 connections).

I would be grateful for any help.

Answer 1

It is strange, but it works well when I create HttpHost without port and protocol arguments.

HttpHost host = new HttpHost("hc.apache.org");
HttpRoute route = new HttpRoute(httpHost);
conman.setMaxPerRoute(route, 13);

PS: I have used httpclient-4.2