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  10 <title>mod_lbmethod_bybusyness - Apache HTTP Server Version 2.5</title>
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  21 <p class="apache">Apache HTTP Server Version 2.5</p>
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  25 <a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.5</a> &gt; <a href="./">Modules</a></div>
  26 <div id="page-content">
  27 <div id="preamble"><h1>Apache Module mod_lbmethod_bybusyness</h1>
  28 <div class="toplang">
  29 <p><span>Available Languages: </span><a href="../en/mod/mod_lbmethod_bybusyness.html" title="English">&nbsp;en&nbsp;</a></p>
  30 </div>
  31 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Pending Request Counting load balancer scheduler algorithm for <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code></td></tr>
  32 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
  33 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>lbmethod_bybusyness_module</td></tr>
  34 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_lbmethod_bybusyness.c</td></tr>
  35 <tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Split off from <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code> in 2.3</td></tr></table>
  36 <h3>Summary</h3>
  37
  38 <p>This module does not provide any configuration directives of its own.
  39 It requires the services of <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code>, and
  40 provides the <code>bybusyness</code> load balancing method.</p>
  41 </div>
  42 <div id="quickview"><h3>Topics</h3>
  43 <ul id="topics">
  44 <li><img alt="" src="../images/down.gif" /> <a href="#busyness">Pending Request Counting Algorithm</a></li>
  45 </ul><h3 class="directives">Directives</h3>
  46 <p>This module provides no
  47             directives.</p>
  48 <h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&amp;list_id=144532&amp;product=Apache%20httpd-2&amp;query_format=specific&amp;order=changeddate%20DESC%2Cpriority%2Cbug_severity&amp;component=mod_lbmethod_bybusyness">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&amp;component=mod_lbmethod_bybusyness">Report a bug</a></li></ul><h3>See also</h3>
  49 <ul class="seealso">
  50 <li><code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code></li>
  51 <li><code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code></li>
  52 </ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
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  54 <div class="section">
  55 <h2><a name="busyness" id="busyness">Pending Request Counting Algorithm</a></h2>
  56
  57
  58
  59     <p>Enabled via <code>lbmethod=bybusyness</code>, this scheduler keeps
  60     track of how many requests each worker is currently assigned at present. A new
  61     request is automatically assigned to the worker with the lowest
  62     number of active requests. This is useful in the case of workers
  63     that queue incoming requests independently of Apache, to ensure that
  64     queue length stays even and a request is always given to the worker
  65     most likely to service it the fastest and reduce latency.</p>
  66
  67     <p>In the case of multiple least-busy workers, the statistics (and
  68     weightings) used by the Request Counting method are used to break the
  69     tie. Over time, the distribution of work will come to resemble that
  70     characteristic of <code>byrequests</code> (as implemented
  71     by <code class="module"><a href="../mod/mod_lbmethod_byrequests.html">mod_lbmethod_byrequests</a></code>).</p>
  72
  73 </div>
  74 </div>
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  76 <p><span>Available Languages: </span><a href="../en/mod/mod_lbmethod_bybusyness.html" title="English">&nbsp;en&nbsp;</a></p>
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