title: Apache HttpClient Max-Connections-per-host Behaviour
body: <p>I have implemented a <strong>REST API</strong> ==> Say ServiceA which in turn calls another remote API ==> Say ServiceB to get the data.</p>
  
  <p>ServiceA is calling ServiceB via <strong>Apache HttpClient</strong> (V3.1)</p>
  
  <p>I am stuck up in complete understanding of below property:</p>
  
  <blockquote>
    <p>DefaultMaxConnectionsPerHost</p>
  </blockquote>
  
  <p>I have configured above property as 10.</p>
  
  <p>Now, according to docs:</p>
  
  <blockquote>
    <p>Defines the maximum number of connections allowed per host configuration. 
      These values only apply to the number of connections from a particular instance 
      of HttpConnectionManager.</p>
  </blockquote>
  
  <p>Theory works well till this point.<br/>
  Let's assume below points in case of ServiceB.</p>
  
  <ol>
  <li>Scenario 1 (ServiceB has single instance of application server)</li>
  </ol>
  
  <p>Straightforward. At any given point of time there can be maximum of 10 concurrent connections to ServiceB from ServiceA.</p>
  
  <ol start="2">
  <li>Scenario 2 (ServiceB has multiple instance of application server)</li>
  </ol>
  
  <p>Since ServiceB has multiple Hosts will be possible to have more than 10 concurrent connections from ServiceA ?
  Or
  <code>DefaultMaxConnectionsPerHost</code> will be identified based on the domain name of ServiceB.</p>
  
  <p>Also, will there be any difference when there is a Load Balancer configured for ServiceB?</p>
  
  <p>Thanks in advance.</p>