mpm.html.en revision 41326e4d330eb9bdf4af7ab021f3ae2cc1fb0146
75f5c2db254c0167a0e396254460de09b775d203trawick<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
75f5c2db254c0167a0e396254460de09b775d203trawick<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
75f5c2db254c0167a0e396254460de09b775d203trawick XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
75f5c2db254c0167a0e396254460de09b775d203trawick This file is generated from xml source: DO NOT EDIT
75f5c2db254c0167a0e396254460de09b775d203trawick XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
75f5c2db254c0167a0e396254460de09b775d203trawick<title>Multi-Processing Modules (MPMs) - Apache HTTP Server Version 2.5</title>
75f5c2db254c0167a0e396254460de09b775d203trawick<link href="/style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
75f5c2db254c0167a0e396254460de09b775d203trawick<link href="/style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
75f5c2db254c0167a0e396254460de09b775d203trawick<link href="/style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="/style/css/prettify.css" />
75f5c2db254c0167a0e396254460de09b775d203trawick<script src="/style/scripts/prettify.min.js" type="text/javascript">
75f5c2db254c0167a0e396254460de09b775d203trawick<link href="/images/favicon.ico" rel="shortcut icon" /></head>
75f5c2db254c0167a0e396254460de09b775d203trawick<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p>
75f5c2db254c0167a0e396254460de09b775d203trawick<div class="up"><a href="./"><img title="<-" alt="<-" src="/images/left.gif" /></a></div>
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.5</a></div><div id="page-content"><div id="preamble"><h1>Multi-Processing Modules (MPMs)</h1>
75f5c2db254c0167a0e396254460de09b775d203trawick<p><span>Available Languages: </span><a href="/de/mpm.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/en/mpm.html" title="English"> en </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/es/mpm.html" hreflang="es" rel="alternate" title="Espa�ol"> es </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/fr/mpm.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/ja/mpm.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/ko/mpm.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/tr/mpm.html" hreflang="tr" rel="alternate" title="T�rk�e"> tr </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/zh-cn/mpm.html" hreflang="zh-cn" rel="alternate" title="Simplified Chinese"> zh-cn </a></p>
75f5c2db254c0167a0e396254460de09b775d203trawick<p>This document describes what a Multi-Processing Module is and
75f5c2db254c0167a0e396254460de09b775d203trawickhow they are used by the Apache HTTP Server.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick<div id="quickview"><ul id="toc"><li><img alt="" src="/images/down.gif" /> <a href="#introduction">Introduction</a></li>
75f5c2db254c0167a0e396254460de09b775d203trawick<li><img alt="" src="/images/down.gif" /> <a href="#defaults">MPM Defaults</a></li>
75f5c2db254c0167a0e396254460de09b775d203trawick<li><img alt="" src="/images/down.gif" /> <a href="#static">Building an MPM as a static module</a></li>
75f5c2db254c0167a0e396254460de09b775d203trawick<li><img alt="" src="/images/down.gif" /> <a href="#dynamic">Building an MPM as a DSO module</a></li>
75f5c2db254c0167a0e396254460de09b775d203trawick</ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
75f5c2db254c0167a0e396254460de09b775d203trawick<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
75f5c2db254c0167a0e396254460de09b775d203trawick<h2><a name="introduction" id="introduction">Introduction</a></h2>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>The Apache HTTP Server is designed to be a powerful and
75f5c2db254c0167a0e396254460de09b775d203trawick flexible web server that can work on a very wide variety of
75f5c2db254c0167a0e396254460de09b775d203trawick platforms in a range of different environments. Different
75f5c2db254c0167a0e396254460de09b775d203trawick platforms and different environments often require different
75f5c2db254c0167a0e396254460de09b775d203trawick features, or may have different ways of implementing the same
75f5c2db254c0167a0e396254460de09b775d203trawick feature most efficiently. Apache httpd has always accommodated a wide
75f5c2db254c0167a0e396254460de09b775d203trawick variety of environments through its modular design. This design
75f5c2db254c0167a0e396254460de09b775d203trawick allows the webmaster to choose which features will be included
75f5c2db254c0167a0e396254460de09b775d203trawick in the server by selecting which modules to load either at
75f5c2db254c0167a0e396254460de09b775d203trawick compile-time or at run-time.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>Apache HTTP Server 2.0 extends this modular design to the most basic
75f5c2db254c0167a0e396254460de09b775d203trawick functions of a web server. The server ships with a selection of
75f5c2db254c0167a0e396254460de09b775d203trawick Multi-Processing Modules (MPMs) which are responsible for
75f5c2db254c0167a0e396254460de09b775d203trawick binding to network ports on the machine, accepting requests,
75f5c2db254c0167a0e396254460de09b775d203trawick and dispatching children to handle the requests.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>Extending the modular design to this level of the server
75f5c2db254c0167a0e396254460de09b775d203trawick allows two important benefits:</p>
75f5c2db254c0167a0e396254460de09b775d203trawick <li>Apache httpd can more cleanly and efficiently support a wide
75f5c2db254c0167a0e396254460de09b775d203trawick variety of operating systems. In particular, the Windows
75f5c2db254c0167a0e396254460de09b775d203trawick version of the server is now much more efficient, since
75f5c2db254c0167a0e396254460de09b775d203trawick <code class="module"><a href="/mod/mpm_winnt.html">mpm_winnt</a></code> can use native
75f5c2db254c0167a0e396254460de09b775d203trawick networking features in place of the POSIX layer used in
75f5c2db254c0167a0e396254460de09b775d203trawick Apache httpd 1.3. This benefit also extends to other operating
75f5c2db254c0167a0e396254460de09b775d203trawick systems that implement specialized MPMs.</li>
75f5c2db254c0167a0e396254460de09b775d203trawick <li>The server can be better customized for the needs of the
75f5c2db254c0167a0e396254460de09b775d203trawick particular site. For example, sites that need a great deal of
75f5c2db254c0167a0e396254460de09b775d203trawick scalability can choose to use a threaded MPM like
75f5c2db254c0167a0e396254460de09b775d203trawick <code class="module"><a href="/mod/worker.html">worker</a></code> or <code class="module"><a href="/mod/event.html">event</a></code>, while sites requiring
75f5c2db254c0167a0e396254460de09b775d203trawick stability or compatibility with older software can use a
75f5c2db254c0167a0e396254460de09b775d203trawick <code class="module"><a href="/mod/prefork.html">prefork</a></code>.</li>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>At the user level, MPMs appear much like other Apache httpd
75f5c2db254c0167a0e396254460de09b775d203trawick modules. The main difference is that one and only one MPM must
75f5c2db254c0167a0e396254460de09b775d203trawick be loaded into the server at any time. The list of available
75f5c2db254c0167a0e396254460de09b775d203trawick MPMs appears on the <a href="mod/">module index page</a>.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
75f5c2db254c0167a0e396254460de09b775d203trawick<h2><a name="defaults" id="defaults">MPM Defaults</a></h2>
bcb83ba673a1e4404886c7eae221a629cc27126etrawick<p>The following table lists the default MPMs for various operating
75f5c2db254c0167a0e396254460de09b775d203trawicksystems. This will be the MPM selected if you do not make another
bcb83ba673a1e4404886c7eae221a629cc27126etrawickchoice at compile-time.</p>
bcb83ba673a1e4404886c7eae221a629cc27126etrawick<table class="bordered"><tr><td>Netware</td><td><code class="module"><a href="/mod/mpm_netware.html">mpm_netware</a></code></td></tr>
bcb83ba673a1e4404886c7eae221a629cc27126etrawick<tr class="odd"><td>OS/2</td><td><code class="module"><a href="/mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
bcb83ba673a1e4404886c7eae221a629cc27126etrawick<tr><td>Unix</td><td><code class="module"><a href="/mod/prefork.html">prefork</a></code>, <code class="module"><a href="/mod/worker.html">worker</a></code>, or
75f5c2db254c0167a0e396254460de09b775d203trawick <code class="module"><a href="/mod/event.html">event</a></code>, depending on platform capabilities</td></tr>
75f5c2db254c0167a0e396254460de09b775d203trawick<tr class="odd"><td>Windows</td><td><code class="module"><a href="/mod/mpm_winnt.html">mpm_winnt</a></code></td></tr>
bcb83ba673a1e4404886c7eae221a629cc27126etrawick<div class="note"><p>Here, 'Unix' is used to mean Unix-like operating systems, such as
75f5c2db254c0167a0e396254460de09b775d203trawick<p>In the case of Unix, the decision as to which MPM is installed is
75f5c2db254c0167a0e396254460de09b775d203trawickbased on two questions:</p>
75f5c2db254c0167a0e396254460de09b775d203trawick<p>2. Does the system support thread-safe polling (Specifically, the
75f5c2db254c0167a0e396254460de09b775d203trawickkqueue and epoll functions)?</p>
75f5c2db254c0167a0e396254460de09b775d203trawick<p>If the answer to both questions is 'yes', the default MPM is
75f5c2db254c0167a0e396254460de09b775d203trawick<code class="module"><a href="/mod/event.html">event</a></code>.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick<p>If The answer to #1 is 'yes', but the answer to #2 is 'no', the
75f5c2db254c0167a0e396254460de09b775d203trawickdefault will be <code class="module"><a href="/mod/worker.html">worker</a></code>.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick<p>If the answer to both questions is 'no', then the default MPM will be
75f5c2db254c0167a0e396254460de09b775d203trawick<code class="module"><a href="/mod/prefork.html">prefork</a></code>.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick<p>In practical terms, this means that the default will almost always be
75f5c2db254c0167a0e396254460de09b775d203trawick<code class="module"><a href="/mod/event.html">event</a></code>, as all modern operating systems support these
75f5c2db254c0167a0e396254460de09b775d203trawicktwo features.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
75f5c2db254c0167a0e396254460de09b775d203trawick<h2><a name="static" id="static">Building an MPM as a static module</a></h2>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>MPMs can be built as static modules on all platforms. A single MPM
75f5c2db254c0167a0e396254460de09b775d203trawick is chosen at build time and linked into the server. The server must
75f5c2db254c0167a0e396254460de09b775d203trawick be rebuilt in order to change the MPM.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>To override the default MPM choice, use the
75f5c2db254c0167a0e396254460de09b775d203trawick <code class="program"><a href="/programs/configure.html">configure</a></code> script. <em>NAME</em> is the name of the
75f5c2db254c0167a0e396254460de09b775d203trawick desired MPM.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>Once the server has been compiled, it is possible to determine which MPM
75f5c2db254c0167a0e396254460de09b775d203trawick was chosen by using <code>/httpd -l</code>. This command will list every
75f5c2db254c0167a0e396254460de09b775d203trawick module that is compiled into the server, including the MPM.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
75f5c2db254c0167a0e396254460de09b775d203trawick<h2><a name="dynamic" id="dynamic">Building an MPM as a DSO module</a></h2>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>On Unix and similar platforms, MPMs can be built as DSO modules and
75f5c2db254c0167a0e396254460de09b775d203trawick dynamically loaded into the server in the same manner as other DSO
75f5c2db254c0167a0e396254460de09b775d203trawick modules. Building MPMs as DSO modules allows the MPM to be changed by
75f5c2db254c0167a0e396254460de09b775d203trawick updating the <code class="directive"><a href="/mod/mod_so.html#loadmodule">LoadModule</a></code> directive
75f5c2db254c0167a0e396254460de09b775d203trawick for the MPM instead of by rebuilding the server.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick <pre class="prettyprint lang-config">LoadModule mpm_prefork_module modules/mod_mpm_prefork.so</pre>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>Attempting to <code class="directive"><a href="/mod/mod_so.html#loadmodule">LoadModule</a></code>
75f5c2db254c0167a0e396254460de09b775d203trawick more than one MPM will result in a startup failure with the
75f5c2db254c0167a0e396254460de09b775d203trawick following error.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick <div class="example"><p><code>AH00534: httpd: Configuration error: More than one MPM
75f5c2db254c0167a0e396254460de09b775d203trawick <p>This feature is enabled using the
75f5c2db254c0167a0e396254460de09b775d203trawick <code>--enable-mpms-shared</code> option of the <code class="program"><a href="/programs/configure.html">configure</a></code>
75f5c2db254c0167a0e396254460de09b775d203trawick With argument <code><em>all</em></code>, all possible MPMs for the platform
75f5c2db254c0167a0e396254460de09b775d203trawick will be installed. Alternately, a list of MPMs can be specified as the
75f5c2db254c0167a0e396254460de09b775d203trawick argument.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick <p>The default MPM, either selected automatically or specified with the
75f5c2db254c0167a0e396254460de09b775d203trawick <code>--with-mpm</code> option of the <code class="program"><a href="/programs/configure.html">configure</a></code>
75f5c2db254c0167a0e396254460de09b775d203trawick script, will be loaded in the generated server configuration file. Edit the
75f5c2db254c0167a0e396254460de09b775d203trawick <code class="directive"><a href="/mod/mod_so.html#loadmodule">LoadModule</a></code> directive to select a
75f5c2db254c0167a0e396254460de09b775d203trawick different MPM.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick<p><span>Available Languages: </span><a href="/de/mpm.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/en/mpm.html" title="English"> en </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/es/mpm.html" hreflang="es" rel="alternate" title="Espa�ol"> es </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/fr/mpm.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/ja/mpm.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/ko/mpm.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/tr/mpm.html" hreflang="tr" rel="alternate" title="T�rk�e"> tr </a> |
75f5c2db254c0167a0e396254460de09b775d203trawick<a href="/zh-cn/mpm.html" hreflang="zh-cn" rel="alternate" title="Simplified Chinese"> zh-cn </a></p>
75f5c2db254c0167a0e396254460de09b775d203trawick</div><div class="top"><a href="#page-header"><img src="/images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
75f5c2db254c0167a0e396254460de09b775d203trawick<script type="text/javascript"><!--//--><![CDATA[//><!--
75f5c2db254c0167a0e396254460de09b775d203trawickvar comments_shortname = 'httpd';
75f5c2db254c0167a0e396254460de09b775d203trawickvar comments_identifier = 'http://httpd.apache.org/docs/trunk/mpm.html';
75f5c2db254c0167a0e396254460de09b775d203trawick(function(w, d) {
75f5c2db254c0167a0e396254460de09b775d203trawick if (w.location.hostname.toLowerCase() == "httpd.apache.org") {
75f5c2db254c0167a0e396254460de09b775d203trawick d.write('<div id="comments_thread"><\/div>');
75f5c2db254c0167a0e396254460de09b775d203trawick var s = d.createElement('script');
75f5c2db254c0167a0e396254460de09b775d203trawick s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier;
75f5c2db254c0167a0e396254460de09b775d203trawick (d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s);
75f5c2db254c0167a0e396254460de09b775d203trawick d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>');
75f5c2db254c0167a0e396254460de09b775d203trawick})(window, document);
75f5c2db254c0167a0e396254460de09b775d203trawick<p class="apache">Copyright 2014 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
75f5c2db254c0167a0e396254460de09b775d203trawick<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p></div><script type="text/javascript"><!--//--><![CDATA[//><!--
75f5c2db254c0167a0e396254460de09b775d203trawickif (typeof(prettyPrint) !== 'undefined') {
75f5c2db254c0167a0e396254460de09b775d203trawick prettyPrint();