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15 <p class="apache">Apache HTTP Server Version 2.1</p>
16 <img alt="" src="./images/feather.gif" /></div>
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19 <a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs-project/">Documentation</a> > <a href="./">Version 2.1</a></div><div id="page-content"><div id="preamble"><h1>Multi-Processing Modules (MPMs)</h1>
21 <p><span>Available Languages: </span><a href="./en/mpm.html" title="English"> en </a> |
22 <a href="./es/mpm.html" hreflang="es" rel="alternate" title="Español"> es </a> |
23 <a href="./ja/mpm.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
24 <a href="./ko/mpm.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
27 <p>This document describes what a Multi-Processing Module is and
28 how they are used by the Apache HTTP Server.</p>
30 <div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#introduction">Introduction</a></li>
31 <li><img alt="" src="./images/down.gif" /> <a href="#choosing">Choosing an MPM</a></li>
32 <li><img alt="" src="./images/down.gif" /> <a href="#defaults">MPM Defaults</a></li>
34 <div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
36 <h2><a name="introduction" id="introduction">Introduction</a></h2>
38 <p>The Apache HTTP Server is designed to be a powerful and
39 flexible web server that can work on a very wide variety of
40 platforms in a range of different environments. Different
41 platforms and different environments often require different
42 features, or may have different ways of implementing the same
43 feature most efficiently. Apache has always accommodated a wide
44 variety of environments through its modular design. This design
45 allows the webmaster to choose which features will be included
46 in the server by selecting which modules to load either at
47 compile-time or at run-time.</p>
49 <p>Apache 2.0 extends this modular design to the most basic
50 functions of a web server. The server ships with a selection of
51 Multi-Processing Modules (MPMs) which are responsible for
52 binding to network ports on the machine, accepting requests,
53 and dispatching children to handle the requests.</p>
55 <p>Extending the modular design to this level of the server
56 allows two important benefits:</p>
59 <li>Apache can more cleanly and efficiently support a wide
60 variety of operating systems. In particular, the Windows
61 version of Apache is now much more efficient, since
62 <code class="module"><a href="./mod/mpm_winnt.html">mpm_winnt</a></code> can use native
63 networking features in place of the POSIX layer used in
64 Apache 1.3. This benefit also extends to other operating
65 systems that implement specialized MPMs.</li>
67 <li>The server can be better customized for the needs of the
68 particular site. For example, sites that need a great deal of
69 scalability can choose to use a threaded MPM like
70 <code class="module"><a href="./mod/worker.html">worker</a></code>, while sites requiring
71 stability or compatibility with older software can use a
72 <code class="module"><a href="./mod/prefork.html">prefork</a></code>. In addition,
73 special features like serving different hosts under different
74 userids (<code class="module"><a href="./mod/perchild.html">perchild</a></code>) can be
78 <p>At the user level, MPMs appear much like other Apache
79 modules. The main difference is that one and only one MPM must
80 be loaded into the server at any time. The list of available
81 MPMs appears on the <a href="mod/">module index page</a>.</p>
83 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
85 <h2><a name="choosing" id="choosing">Choosing an MPM</a></h2>
87 <p>MPMs must be chosen during configuration, and compiled into
88 the server. Compilers are capable of optimizing a lot of
89 functions if threads are used, but only if they know that
90 threads are being used. Because some MPMs use threads on Unix
91 and others don't, Apache will always perform better if the MPM
92 is chosen at configuration time and built into Apache.</p>
94 <p>To actually choose the desired MPM, use the argument
95 --with-mpm= <em>NAME</em> with the <code class="program"><a href="./programs/configure.html">configure</a></code> script.
96 <em>NAME</em> is the name of the desired MPM.</p>
98 <p>Once the server has been compiled, it is possible to
99 determine which MPM was chosen by using <code>./httpd
100 -l</code>. This command will list every module that is compiled
101 into the server, including the MPM.</p>
102 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
103 <div class="section">
104 <h2><a name="defaults" id="defaults">MPM Defaults</a></h2>
106 <p>The following table lists the default MPMs for various operating
107 systems. This will be the MPM selected if you do not make another
108 choice at compile-time.</p>
112 <tr><td>BeOS</td><td><code class="module"><a href="./mod/beos.html">beos</a></code></td></tr>
113 <tr><td>Netware</td><td><code class="module"><a href="./mod/mpm_netware.html">mpm_netware</a></code></td></tr>
114 <tr><td>OS/2</td><td><code class="module"><a href="./mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
115 <tr><td>Unix</td><td><code class="module"><a href="./mod/prefork.html">prefork</a></code></td></tr>
116 <tr><td>Windows</td><td><code class="module"><a href="./mod/mpm_winnt.html">mpm_winnt</a></code></td></tr>
119 <div class="bottomlang">
120 <p><span>Available Languages: </span><a href="./en/mpm.html" title="English"> en </a> |
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123 <a href="./ko/mpm.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
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125 <p class="apache">Copyright 1995-2005 The Apache Software Foundation or its licensors, as applicable.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
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