Question

ThreadSafeClientConnManager is deprecated and a new method is introduced PoolingClientConnectionManager.

The documentation of PoolingClientConnectionManager says

Manages a pool of client connections and is able to service connection
requests from multiple execution threads. Connections are pooled on a
per route basis.

My Question

What is the meaning of per route basis here?

Answer 1

It refers to the HttpRoute. The HttpRoute is to delineate multiple applications running on the same web server.

http://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/conn/routing/HttpRoute.html

It is used like below:

ClientConnectionRequest connRequest = connMrg.requestConnection(
        new HttpRoute(new HttpHost("localhost", 80)), null);
ManagedClientConnection conn = connRequest.getConnection(10, TimeUnit.SECONDS);
try {
    BasicHttpRequest request = new BasicHttpRequest("GET", "/");
    conn.sendRequestHeader(request);
    HttpResponse response = conn.receiveResponseHeader();
    conn.receiveResponseEntity(response);
    HttpEntity entity = response.getEntity();
    if (entity != null) {
        BasicManagedEntity managedEntity = new BasicManagedEntity(entity, conn, true);
        // Replace entity
        response.setEntity(managedEntity);
    }
    // Do something useful with the response
    // The connection will be released automatically 
    // as soon as the response content has been consumed
} catch (IOException ex) {
    // Abort connection upon an I/O error.
    conn.abortConnection();
    throw ex;
}

source: http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html