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apache/docs/manual/mod/perchild.html.en
André Malo a75d816777 the MPM module docs:
- <em> -> <var>
- a little other markup changes


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<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
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--><title>perchild - Apache HTTP Server</title><link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /><link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /><link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link href="../images/favicon.ico" rel="shortcut icon" /></head><body><div id="page-header"><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><p class="apache">Apache HTTP Server Version 2.0</p><img alt="" src="../images/feather.gif" /></div><div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="../images/left.gif" /></a></div><div id="path"><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-project/">Documentation</a> &gt; <a href="../">Version 2.0</a> &gt; <a href="./">Modules</a></div><div id="page-content"><div id="preamble"><h1>Apache Module perchild</h1><table class="module"><tr><th><a href="module-dict.html#Description">Description:
</a></th><td>Multi-Processing Module allowing for daemon processes
serving requests to be assigned a variety of different
userids</td></tr><tr><th><a href="module-dict.html#Status">Status:
</a></th><td>MPM</td></tr><tr><th><a href="module-dict.html#ModuleIdentifier">Module<EFBFBD>Identifier:
</a></th><td>mpm_perchild_module</td></tr><tr><th><a href="module-dict.html#SourceFile">Source<EFBFBD>File:
</a></th><td>perchild.c</td></tr></table><h3>Summary</h3>
<div class="warning">
This MPM does not currently work on most platforms. Work is ongoing to
make it functional.
</div>
<p>This Multi-Processing Module (MPM) implements a hybrid
multi-process, multi-threaded web server. A fixed number of
processes create threads to handle requests. Fluctuations in
load are handled by increasing or decreasing the number of
threads in each process.</p>
<p>A single control process launches the number of child processes
indicated by the <code class="directive"><a href="../mod/mpm_common.html#numservers">NumServers</a></code> directive at server
startup. Each child process creates threads as specified in the
<code class="directive"><a href="../mod/mpm_common.html#startthreads">StartThreads</a></code> directive.
The individual threads then
listen for connections and serve them when they arrive.</p>
<p>Apache always tries to maintain a pool of <dfn>spare</dfn> or
idle server threads, which stand ready to serve incoming
requests. In this way, clients do not need to wait for new
threads to be created. For each child process, Apache assesses
the number of idle threads and creates or destroys threads to
keep this number within the boundaries specified by
<code class="directive"><a href="../mod/mpm_common.html#minsparethreads">MinSpareThreads</a></code>
and <code class="directive"><a href="../mod/mpm_common.html#maxsparethreads">MaxSpareThreads</a></code>.
Since this process is very self-regulating, it is rarely
necessary to modify these directives from their default values.
The maximum number of clients that may be served simultaneously
is determined by multiplying the number of server processes
that will be created (<code class="directive"><a href="../mod/mpm_common.html#numservers">NumServers</a></code>) by the maximum
number of threads created in each process
(<code class="directive"><a href="../mod/mpm_common.html#maxthreadsperchild">MaxThreadsPerChild</a></code>).</p>
<p>While the parent process is usually started as root under
Unix in order to bind to port 80, the child processes and
threads are 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 the privileges of the Apache child processes. The child
processes must be able to read all the content that will be
served, but should have as few privileges beyond that as
possible. In addition, unless <a href="../suexec.html">suexec</a> is used, these directives also
set the privileges which will be inherited by CGI scripts.</p>
<p><code class="directive"><a href="../mod/mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></code>
controls how frequently the
server recycles processes by killing old ones and launching new
ones.</p>
<p>In addition it adds the extra ability to specify that
specific processes should serve requests under different
userids. These processes can then be associated with specific
virtual hosts.</p>
</div><div id="quickview"><h3 class="directives">Directives</h3><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#assignuserid">AssignUserId</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#childperuserid">ChildPerUserId</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#coredumpdirectory">CoreDumpDirectory</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#group">Group</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#listen">Listen</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#listenbacklog">ListenBacklog</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#lockfile">LockFile</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxsparethreads">MaxSpareThreads</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxthreadsperchild">MaxThreadsPerChild</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#minsparethreads">MinSpareThreads</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#numservers">NumServers</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#pidfile">PidFile</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#scoreboardfile">ScoreBoardFile</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#sendbuffersize">SendBufferSize</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#startthreads">StartThreads</a></li>
<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#user">User</a></li>
</ul><h3>See also</h3><ul class="seealso"><li><a href="../bind.html">Setting which addresses and
ports Apache uses</a>
</li></ul></div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div><div class="directive-section"><h2><a name="AssignUserId" id="AssignUserId">AssignUserId</a> <a name="assignuserid" id="assignuserid">Directive</a></h2><table class="directive"><tr><th><a href="directive-dict.html#Description">Description:
</a></th><td /></tr><tr><th><a href="directive-dict.html#Syntax">Syntax:
</a></th><td><code>AssignUserID <var>user_id</var> <var>group_id</var></code></td></tr><tr><th><a href="directive-dict.html#Context">Context:
</a></th><td>virtual host</td></tr><tr><th><a href="directive-dict.html#Status">Status:
</a></th><td>MPM</td></tr><tr><th><a href="directive-dict.html#Module">Module:
</a></th><td>perchild</td></tr></table>
<p>Tie a virtual host to a specific child process. Requests addressed to
the virtual host where this directive appears will be served by the process
running with the specified user and group id.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div><div class="directive-section"><h2><a name="ChildPerUserId" id="ChildPerUserId">ChildPerUserId</a> <a name="childperuserid" id="childperuserid">Directive</a></h2><table class="directive"><tr><th><a href="directive-dict.html#Description">Description:
</a></th><td /></tr><tr><th><a href="directive-dict.html#Syntax">Syntax:
</a></th><td><code>ChildPerUserID <var>user_id</var>
<var>group_id</var> <var>num_children</var></code></td></tr><tr><th><a href="directive-dict.html#Context">Context:
</a></th><td>server config</td></tr><tr><th><a href="directive-dict.html#Status">Status:
</a></th><td>MPM</td></tr><tr><th><a href="directive-dict.html#Module">Module:
</a></th><td>perchild</td></tr></table>
<p>Specify a user id and group id for a number of child processes. The third
argument, num_children, is the number of child processes to start with the
specified user and group. It does <strong>not</strong> represent a specific
child number. If the total number of child processes, found by totaling all of
the third arguments to all ChildPerUserId directives in the config file, is
less than <code class="directive"><a href="../mod/mpm_common.html#numservers">NumServers</a></code>, then all
remaining children will inherit 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> settings from the main server </p>
</div></div><div id="footer"><p class="apache">Maintained by the <a href="http://httpd.apache.org/docs-project/">Apache HTTP Server Documentation Project</a></p><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></body></html>