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<html xmlns="http://www.w3.org/TR/xhtml1/strict"><head><!--
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--><title>perchild - Apache HTTP Server</title><link href="../style/manual.css" type="text/css" rel="stylesheet"/></head><body><blockquote><div align="center"><img alt="[APACHE DOCUMENTATION]" src="../images/sub.gif"/><h3>Apache HTTP Server Version 2.0</h3></div><h1 align="center">Apache Module perchild</h1><table cellspacing="1" cellpadding="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td valign="top"><span class="help">Description:</span></td><td>Multi-Processing Module allowing for daemon processes
serving requests to be assigned a variety of different
userids</td></tr><tr><td><a href="module-dict.html#Status" class="help">Status:</a></td><td>MPM</td></tr><tr><td><a href="module-dict.html#ModuleIdentifier" class="help">Module Identifier:</a></td><td>mpm_perchild_module</td></tr></table></td></tr></table><h2>Summary</h2>
<blockquote><table><tr><td bgcolor="#ffe5f5">
This MPM does not currently work on most platforms. Work is ongoing to
make it functional.
</td></tr></table></blockquote>
<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 <a href="mpm_common.html#numservers" class="directive"><code class="directive">NumServers</code></a> directive at server
startup. Each child process creates threads as specified in the
<code>StartThreads</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 <em>spare</em> 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>MinSpareThreads</code> and <code>MaxSpareThreads</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>NumServers</code>) by the maximum
number of threads created in each process
(<code>MaxThreadsPerChild</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>User</code> and <code>Group</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>MaxRequestsPerChild</code> controls how frequently the
server recycles processes by killing old ones and launching new
ones.</p>
<p>See also: <a href="../bind.html">Setting which addresses and
ports Apache uses</a>.</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>
<h2>Directives</h2><ul><li><a href="#assignuserid">AssignUserId</a></li><li><a href="#childperuserid">ChildPerUserId</a></li><li><a href="mpm_common.html#coredumpdirectory">CoreDumpDirectory</a></li><li><a href="mpm_common.html#group">Group</a></li><li><a href="mpm_common.html#listen">Listen</a></li><li><a href="mpm_common.html#listenbacklog">ListenBacklog</a></li><li><a href="mpm_common.html#lockfile">LockFile</a></li><li><a href="mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></li><li><a href="mpm_common.html#maxsparethreads">MaxSpareThreads</a></li><li><a href="mpm_common.html#maxthreadsperchild">MaxThreadsPerChild</a></li><li><a href="mpm_common.html#minsparethreads">MinSpareThreads</a></li><li><a href="mpm_common.html#numservers">NumServers</a></li><li><a href="mpm_common.html#pidfile">PidFile</a></li><li><a href="mpm_common.html#scoreboardfile">ScoreBoardFile</a></li><li><a href="mpm_common.html#sendbuffersize">SendBufferSize</a></li><li><a href="mpm_common.html#startthreads">StartThreads</a></li><li><a href="mpm_common.html#user">User</a></li></ul><hr/><h2><a name="AssignUserId">AssignUserId</a> <a name="assignuserid">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td><strong>Description: </strong></td><td/></tr><tr><td><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>AssignUserID <em>user_id</em> <em>group_id</em></td></tr><tr><td><a href="directive-dict.html#Context" class="help">Context:</a></td><td>virtual host</td></tr><tr><td><a href="directive-dict.html#Status" class="help">Status:</a></td><td>MPM</td></tr><tr><td><a href="directive-dict.html#Module" class="help">Module:</a></td><td>perchild</td></tr></table></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>
<hr/><h2><a name="ChildPerUserId">ChildPerUserId</a> <a name="childperuserid">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td><strong>Description: </strong></td><td/></tr><tr><td><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>ChildPerUserID <em>user_id</em>
<em>group_id</em> <em>child_id</em></td></tr><tr><td><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config</td></tr><tr><td><a href="directive-dict.html#Status" class="help">Status:</a></td><td>MPM</td></tr><tr><td><a href="directive-dict.html#Module" class="help">Module:</a></td><td>perchild</td></tr></table></td></tr></table>
<p>Specify a user id and group id for a specific child process. The number of
children if set by the <a href="mpm_common.html#numservers">NumServers</a>
directive. For example, the default value for <a href="mpm_common.html#numservers">NumServers</a> is 5 and that means
children ids 1,2,3,4 and 5 are available for assigment. If a child does not
have an associated ChildPerUserID, it inherits the <a href="mpm_common.html#user">User</a> and <a href="mpm_common.html#group">Group</a> settings from the main server </p>
<hr/><h3 align="center">Apache HTTP Server Version 2.0</h3><a href="./"><img alt="Index" src="../images/index.gif"/></a><a href="../"><img alt="Home" src="../images/home.gif"/></a></blockquote></body></html>
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