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5a58787efeb02a1c3f06569d019ad81fd2efa06end<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/directives.html">Directives</a> | <a href="/faq/">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p>
52fff662005b1866a3ff09bb6c902800c5cc6dedjerenkrantz<p class="apache">Apache HTTP Server Version 2.3</p>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<div class="up"><a href="./"><img title="<-" alt="<-" src="/images/left.gif" /></a></div>
4b5981e276e93df97c34e4da05ca5cf8bbd937dand<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 2.3</a> > <a href="./">Modules</a></div>
ad74a0524a06bfe11b7de9e3b4ce7233ab3bd3f7nd<p><span>Available Languages: </span><a href="/de/mod/prefork.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
ad74a0524a06bfe11b7de9e3b4ce7233ab3bd3f7nd<a href="/en/mod/prefork.html" title="English"> en </a> |
ad74a0524a06bfe11b7de9e3b4ce7233ab3bd3f7nd<a href="/ja/mod/prefork.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Implements a non-threaded, pre-forking web server</td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="module-dict.html#Status">Status:</a></th><td>MPM</td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="module-dict.html#ModuleIdentifier">Module�Identifier:</a></th><td>mpm_prefork_module</td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="module-dict.html#SourceFile">Source�File:</a></th><td>prefork.c</td></tr></table>
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive <p>This Multi-Processing Module (MPM) implements a non-threaded,
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive pre-forking web server that handles requests in a manner similar
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive to Apache 1.3. It is appropriate for sites that need to avoid
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive threading for compatibility with non-thread-safe libraries. It
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive is also the best MPM for isolating each request, so that a problem
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive with a single request will not affect any other.</p>
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive <p>This MPM is very self-regulating, so it is rarely necessary to
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive adjust its configuration directives. Most important is that
97a9a944b5887e91042b019776c41d5dd74557aferikabele <code class="directive"><a href="/mod/mpm_common.html#maxclients">MaxClients</a></code> be big enough to
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive handle as many simultaneous requests as you expect to receive, but
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive small enough to assure that there is enough physical RAM for all
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive processes.</p>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<div id="quickview"><h3 class="directives">Directives</h3>
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#acceptmutex">AcceptMutex</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#coredumpdirectory">CoreDumpDirectory</a></li>
deeee6bb6fd94c0ba5f3730b58abd9d299c89ccdnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#enableexceptionhook">EnableExceptionHook</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#group">Group</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#listen">Listen</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#listenbacklog">ListenBacklog</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#lockfile">LockFile</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#maxclients">MaxClients</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#maxmemfree">MaxMemFree</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/down.gif" /> <a href="#maxspareservers">MaxSpareServers</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/down.gif" /> <a href="#minspareservers">MinSpareServers</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#pidfile">PidFile</a></li>
2bc7f1cf720973a67f8ff7a8d523e40569ae5b6cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#receivebuffersize">ReceiveBufferSize</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#scoreboardfile">ScoreBoardFile</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#sendbuffersize">SendBufferSize</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#serverlimit">ServerLimit</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#startservers">StartServers</a></li>
117c1f888a14e73cdd821dc6c23eb0411144a41cnd<li><img alt="" src="/images/right.gif" /> <a href="mpm_common.html#user">User</a></li>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<li><img alt="" src="/images/down.gif" /> <a href="#how-it-works">How it Works</a></li>
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd<li><a href="/bind.html">Setting which addresses and ports Apache
5a58787efeb02a1c3f06569d019ad81fd2efa06end<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<h2><a name="how-it-works" id="how-it-works">How it Works</a></h2>
06ba4a61654b3763ad65f52283832ebf058fdf1cslive <p>A single control process is responsible for launching child
06ba4a61654b3763ad65f52283832ebf058fdf1cslive processes which listen for connections and serve them when they
ea8a727ff298d2f5368b55b7ae8d87091ae106e7nd arrive. Apache always tries to maintain several <dfn>spare</dfn>
06ba4a61654b3763ad65f52283832ebf058fdf1cslive or idle server processes, which stand ready to serve incoming
06ba4a61654b3763ad65f52283832ebf058fdf1cslive requests. In this way, clients do not need to wait for a new
06ba4a61654b3763ad65f52283832ebf058fdf1cslive child processes to be forked before their requests can be
06ba4a61654b3763ad65f52283832ebf058fdf1cslive served.</p>
97a9a944b5887e91042b019776c41d5dd74557aferikabele <p>The <code class="directive"><a href="/mod/mpm_common.html#startservers">StartServers</a></code>,
97a9a944b5887e91042b019776c41d5dd74557aferikabele <code class="directive"><a href="#minspareservers">MinSpareServers</a></code>,
97a9a944b5887e91042b019776c41d5dd74557aferikabele <code class="directive"><a href="#maxspareservers">MaxSpareServers</a></code>, and
97a9a944b5887e91042b019776c41d5dd74557aferikabele <code class="directive"><a href="/mod/mpm_common.html#maxclients">MaxClients</a></code> regulate how
06ba4a61654b3763ad65f52283832ebf058fdf1cslive the parent process creates children to serve requests. In general,
06ba4a61654b3763ad65f52283832ebf058fdf1cslive Apache is very self-regulating, so most sites do not need to
06ba4a61654b3763ad65f52283832ebf058fdf1cslive adjust these directives from their default values. Sites which
06ba4a61654b3763ad65f52283832ebf058fdf1cslive need to serve more than 256 simultaneous requests may need to
97a9a944b5887e91042b019776c41d5dd74557aferikabele increase <code class="directive"><a href="/mod/mpm_common.html#maxclients">MaxClients</a></code>,
97a9a944b5887e91042b019776c41d5dd74557aferikabele while sites with limited memory may need to decrease <code class="directive"><a href="/mod/mpm_common.html#maxclients">MaxClients</a></code> to keep the server from
06ba4a61654b3763ad65f52283832ebf058fdf1cslive thrashing (swapping memory to disk and back). More information
06ba4a61654b3763ad65f52283832ebf058fdf1cslive about tuning process creation is provided in the <a href="/misc/perf-tuning.html">performance hints</a>
06ba4a61654b3763ad65f52283832ebf058fdf1cslive documentation.</p>
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd <p>While the parent process is usually started as <code>root</code>
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd under Unix in order to bind to port 80, the child processes are
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd launched by Apache as a less-privileged user. The <code class="directive"><a href="/mod/mpm_common.html#user">User</a></code> and <code class="directive"><a href="/mod/mpm_common.html#group">Group</a></code> directives are used to set
06ba4a61654b3763ad65f52283832ebf058fdf1cslive the privileges of the Apache child processes. The child processes
06ba4a61654b3763ad65f52283832ebf058fdf1cslive must be able to read all the content that will be served, but
9b6a3a558cc90ffdaa0b50bd02546ffec424ded7slive should have as few privileges beyond that as possible.</p>
97a9a944b5887e91042b019776c41d5dd74557aferikabele <p><code class="directive"><a href="/mod/mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></code>
06ba4a61654b3763ad65f52283832ebf058fdf1cslive controls how frequently the server recycles processes by killing
06ba4a61654b3763ad65f52283832ebf058fdf1cslive old ones and launching new ones.</p>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<div class="directive-section"><h2><a name="MaxSpareServers" id="MaxSpareServers">MaxSpareServers</a> <a name="maxspareservers" id="maxspareservers">Directive</a></h2>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of idle child server processes</td></tr>
9fc1345bb54ea7f68c2e59ff3a618c1237a30918yoshiki<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxSpareServers <var>number</var></code></td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxSpareServers 10</code></td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>prefork</td></tr>
06ba4a61654b3763ad65f52283832ebf058fdf1cslive <p>The <code class="directive">MaxSpareServers</code> directive sets the
06ba4a61654b3763ad65f52283832ebf058fdf1cslive desired maximum number of <em>idle</em> child server processes. An
06ba4a61654b3763ad65f52283832ebf058fdf1cslive idle process is one which is not handling a request. If there are
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd more than <code class="directive">MaxSpareServers</code> idle, then the
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd parent process will kill off the excess processes.</p>
06ba4a61654b3763ad65f52283832ebf058fdf1cslive <p>Tuning of this parameter should only be necessary on very
06ba4a61654b3763ad65f52283832ebf058fdf1cslive busy sites. Setting this parameter to a large number is almost
f989aee1278b24f2b6e3a8e3b0935b590349de81jorton always a bad idea. If you are trying to set the value equal to or lower than
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd <code class="directive"><a href="#minspareservers">MinSpareServers</a></code>, Apache
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd will automatically adjust it to <code class="directive">MinSpareServers</code><code> + 1</code>.</p>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<li><code class="directive"><a href="#minspareservers">MinSpareServers</a></code></li>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<li><code class="directive"><a href="/mod/mpm_common.html#startservers">StartServers</a></code></li>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<div class="directive-section"><h2><a name="MinSpareServers" id="MinSpareServers">MinSpareServers</a> <a name="minspareservers" id="minspareservers">Directive</a></h2>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Minimum number of idle child server processes</td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MinSpareServers <var>number</var></code></td></tr>
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MinSpareServers 5</code></td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>prefork</td></tr>
06ba4a61654b3763ad65f52283832ebf058fdf1cslive <p>The <code class="directive">MinSpareServers</code> directive sets the
06ba4a61654b3763ad65f52283832ebf058fdf1cslive desired minimum number of <em>idle</em> child server processes. An
06ba4a61654b3763ad65f52283832ebf058fdf1cslive idle process is one which is not handling a request. If there are
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd fewer than <code class="directive">MinSpareServers</code> idle, then the parent
a63f0ab647ad2ab72efc9bea7a66e24e9ebc5cc2nd process creates new children at a maximum rate of 1 per second.</p>
06ba4a61654b3763ad65f52283832ebf058fdf1cslive <p>Tuning of this parameter should only be necessary on very
06ba4a61654b3763ad65f52283832ebf058fdf1cslive busy sites. Setting this parameter to a large number is almost
06ba4a61654b3763ad65f52283832ebf058fdf1cslive always a bad idea.</p>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<li><code class="directive"><a href="#maxspareservers">MaxSpareServers</a></code></li>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<li><code class="directive"><a href="/mod/mpm_common.html#startservers">StartServers</a></code></li>
ad74a0524a06bfe11b7de9e3b4ce7233ab3bd3f7nd<p><span>Available Languages: </span><a href="/de/mod/prefork.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
ad74a0524a06bfe11b7de9e3b4ce7233ab3bd3f7nd<a href="/en/mod/prefork.html" title="English"> en </a> |
ad74a0524a06bfe11b7de9e3b4ce7233ab3bd3f7nd<a href="/ja/mod/prefork.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
b95ae799514ad86a15610ad75808d7065e9847c9kess<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>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/directives.html">Directives</a> | <a href="/faq/">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p></div>