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365 lines
11 KiB
HTML
365 lines
11 KiB
HTML
<html>
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<META http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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This file is generated from xml source: DO NOT EDIT
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<title>prefork - Apache HTTP Server</title>
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<link href="../style/manual.css" type="text/css" rel="stylesheet">
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</head>
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<body>
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<blockquote>
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<div align="center">
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<img alt="[APACHE DOCUMENTATION]" src="../images/sub.gif"><h3>Apache HTTP Server Version 2.0</h3>
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</div>
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<h1 align="center">Apache Module prefork</h1>
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<table cellspacing="1" cellpadding="0" bgcolor="#cccccc">
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<tr>
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<td>
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<table bgcolor="#ffffff">
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<tr>
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<td><span class="help">Description:</span></td><td>
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<description>Implements a non-threaded, pre-forking web server</description>
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</td>
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</tr>
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<tr>
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<td><a href="module-dict.html#Status" class="help">Status:</a></td><td>MPM</td>
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</tr>
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<tr>
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<td><a href="module-dict.html#ModuleIdentifier" class="help">Module Identifier:</a></td><td>mpm_prefork_module</td>
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</tr>
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</table>
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</td>
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</tr>
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</table>
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<h2>Summary</h2>
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<summary>
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<p>This Multi-Processing Module (MPM) implements a
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non-threaded, pre-forking web server which handles request in a
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manner very similar to the default behavior of Apache 1.3 on
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Unix.</p>
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<p>A single control process is responsible for launching child
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processes which listen for connections and serve them when they
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arrive. Apache always tries to maintain several <em>spare</em>
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or idle server processes, which stand ready to serve incoming
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requests. In this way, clients do not need to wait for a new
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child processes to be forked before their requests can be
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served.</p>
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<p>The <code class="directive"><a href="mpm_common.html#startservers" class="directive">StartServers</a></code>,
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<code class="directive"><a href="#minspareservers" class="directive">MinSpareServers</a></code>,
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<code class="directive"><a href="#maxspareservers" class="directive">MaxSpareServers</a></code>, and
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<code class="directive"><a href="mpm_common.html#maxclients" class="directive">MaxClients</a></code> regulate how
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the parent process creates children to serve requests. In general,
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Apache is very self-regulating, so most sites do not need to
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adjust these directives from their default values. Sites which
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need to serve more than 256 simultaneous requests may need to
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increase <code class="directive"><a href="mpm_common.html#maxclients" class="directive">MaxClients</a></code>,
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while sites with limited memory may need to decrease <code class="directive"><a href="mpm_common.html#maxclients" class="directive">MaxClients</a></code> to keep the server from
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thrashing (swapping memory to disk and back). More information
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about tuning process creation is provided in the <a href="../misc/perf-tuning.html">performance hints</a>
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documentation.</p>
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<p>While the parent process is usually started as root under Unix
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in order to bind to port 80, the child processes are launched by
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Apache as a less-privileged user. The <code class="directive"><a href="mpm_common.html#user" class="directive">User</a></code> and <code class="directive"><a href="mpm_common.html#group" class="directive">Group</a></code> directives are used to set
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the privileges of the Apache child processes. The child processes
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must be able to read all the content that will be served, but
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should have as few privileges beyond that as possible. In
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addition, unless <a href="../suexec.html">suexec</a> is used,
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these directives also set the privileges which will be inherited
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by CGI scripts.</p>
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<p>
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<code class="directive"><a href="mpm_common.html#maxrequestsperchild" class="directive">MaxRequestsPerChild</a></code>
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controls how frequently the server recycles processes by killing
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old ones and launching new ones.</p>
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</summary>
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<p>
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<strong>See also:</strong>
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</p>
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<ul>
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<li>
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<a href="../bind.html">Setting which addresses and
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ports Apache uses</a>
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</li>
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</ul>
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<h2>Directives</h2>
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<ul>
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<li>
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<a href="#acceptmutex">AcceptMutex</a>
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</li>
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<li>
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<a href="mpm_common.html#coredumpdirectory">CoreDumpDirectory</a>
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</li>
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<li>
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<a href="mpm_common.html#listen">Listen</a>
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</li>
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<li>
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<a href="mpm_common.html#listenbacklog">ListenBacklog</a>
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</li>
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<li>
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<a href="mpm_common.html#lockfile">LockFile</a>
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</li>
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<li>
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<a href="mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a>
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</li>
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<li>
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<a href="mpm_common.html#maxspareservers">MaxSpareServers</a>
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</li>
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<li>
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<a href="#maxspareservers">MaxSpareServers</a>
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</li>
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<li>
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<a href="mpm_common.html#minspareservers">MinSpareServers</a>
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</li>
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<li>
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<a href="#minspareservers">MinSpareServers</a>
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</li>
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<li>
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<a href="mpm_common.html#pidfile">PidFile</a>
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</li>
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<li>
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<a href="mpm_common.html#scoreboardfile">ScoreBoardFile</a>
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</li>
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<li>
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<a href="mpm_common.html#sendbuffersize">SendBufferSize</a>
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</li>
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<li>
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<a href="mpm_common.html#serverlimit">ServerLimit</a>
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</li>
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<li>
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<a href="mpm_common.html#startservers">StartServers</a>
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</li>
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<li>
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<a href="mpm_common.html#user">User</a>
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</li>
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</ul>
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<hr>
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<h2>
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<a name="AcceptMutex">AcceptMutex</a> <a name="acceptmutex">Directive</a>
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</h2>
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<table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc">
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<tr>
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<td>
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<table width="100%" bgcolor="#ffffff">
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<tr>
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<td><strong>Description: </strong></td><td>Method that Apache uses to serialize multiple children
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accepting requests on network sockets</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>
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<syntax>AcceptMutex default|<em>method</em>
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</syntax>
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</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Default" class="help">Default:</a></td><td><code>AcceptMutex default</code></td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Status" class="help">Status:</a></td><td>MPM</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Module" class="help">Module:</a></td><td>prefork</td>
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</tr>
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</table>
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</td>
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</tr>
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</table>
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<usage>
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<p>The <code class="directive">AcceptMutex</code> directives sets the
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method that Apache uses to serialize multiple children accepting
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requests on network sockets. Prior to Apache 2.0, the method was
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selectable only at compile time. The optimal method to use is
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highly architecture and platform dependent. For further details,
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see the <a href="../misc/perf-tuning.html">performance tuning</a>
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documentation.</p>
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<p>If this directive is set to <code>default</code>, then the
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compile-time selected default will be used. Other possible
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methods are listed below. Note that not all methods are
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available on all platforms. If a method is specified which is
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not available, a message will be written to the error log
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listing the available methods.</p>
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<dl>
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<dt>
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<code>flock</code>
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</dt>
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<dd>uses the <code>flock(2)</code> system call to lock the
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file defined by the <code class="directive"><a href="mpm_common.html#lockfile" class="directive">LockFile</a></code> directive.</dd>
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<dt>
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<code>fcntl</code>
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</dt>
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<dd>uses the <code>fnctl(2)</code> system call to lock the
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file defined by the <code class="directive"><a href="mpm_common.html#lockfile" class="directive">LockFile</a></code> directive.</dd>
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<dt>
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<code>sysvsem</code>
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</dt>
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<dd>uses SySV-style semaphores to implement the mutex.</dd>
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<dt>
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<code>pthread</code>
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</dt>
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<dd>uses POSIX mutexes as implemented by the POSIX Threads
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(PThreads) specification.</dd>
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</dl>
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</usage>
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<hr>
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<h2>
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<a name="MaxSpareServers">MaxSpareServers</a> <a name="maxspareservers">Directive</a>
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</h2>
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<table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc">
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<tr>
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<td>
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<table width="100%" bgcolor="#ffffff">
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<tr>
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<td><strong>Description: </strong></td><td>Maximum number of idle child server processes</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>
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<syntax>MaxSpareServers <em>number</em>
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<br>
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</syntax>
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</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Default" class="help">Default:</a></td><td><code>MaxSpareServers 10</code></td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Status" class="help">Status:</a></td><td>MPM</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Module" class="help">Module:</a></td><td>prefork</td>
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</tr>
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</table>
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</td>
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</tr>
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</table>
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<usage>
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<p>The <code class="directive">MaxSpareServers</code> directive sets the
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desired maximum number of <em>idle</em> child server processes. An
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idle process is one which is not handling a request. If there are
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more than MaxSpareServers idle, then the parent process will kill
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off the excess processes.</p>
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<p>Tuning of this parameter should only be necessary on very
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busy sites. Setting this parameter to a large number is almost
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always a bad idea.</p>
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</usage>
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<p>
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<strong>See also:</strong>
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</p>
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<ul>
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<li>
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<code class="directive"><a href="#minspareservers" class="directive">MinSpareServers</a></code>
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</li>
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<li>
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<code class="directive"><a href="mpm_common.html#startservers" class="directive">StartServers</a></code>
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</li>
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</ul>
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<hr>
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<h2>
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<a name="MinSpareServers">MinSpareServers</a> <a name="minspareservers">Directive</a>
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</h2>
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<table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc">
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<tr>
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<td>
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<table width="100%" bgcolor="#ffffff">
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<tr>
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<td><strong>Description: </strong></td><td>Minimum number of idle child server processes</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>
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<syntax>MinSpareServers <em>number</em>
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</syntax>
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</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Default" class="help">Default:</a></td><td><code>MinSpareServers 5</code></td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Status" class="help">Status:</a></td><td>MPM</td>
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</tr>
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<tr>
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<td><a href="directive-dict.html#Module" class="help">Module:</a></td><td>prefork</td>
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</tr>
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</table>
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</td>
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</tr>
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</table>
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<usage>
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<p>The <code class="directive">MinSpareServers</code> directive sets the
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desired minimum number of <em>idle</em> child server processes. An
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idle process is one which is not handling a request. If there are
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fewer than MinSpareServers idle, then the parent process creates
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new children at a maximum rate of 1 per second.</p>
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<p>Tuning of this parameter should only be necessary on very
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busy sites. Setting this parameter to a large number is almost
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always a bad idea.</p>
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<p>This directive has no effect on Microsoft Windows.</p>
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</usage>
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<p>
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<strong>See also:</strong>
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</p>
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<ul>
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<li>
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<code class="directive"><a href="#maxspareservers" class="directive">MaxSpareServers</a></code>
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</li>
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<li>
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<code class="directive"><a href="mpm_common.html#startservers" class="directive">StartServers</a></code>
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</li>
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</ul>
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<hr>
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<h3 align="center">Apache HTTP Server Version 2.0</h3>
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<a href="./"><img alt="Index" src="../images/index.gif"></a><a href="../"><img alt="Home" src="../images/home.gif"></a>
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</blockquote>
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</body>
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</html>
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