docs/manual/mod/perchild.html.en - httpd - Git at Google

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 <p class="apache">Apache HTTP Server Version 2.0</p>
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 <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/">Documentation</a> &gt; <a href="../">Version 2.0</a> &gt; <a href="./">Modules</a></div>
 <div id="page-content">
 <div class="retired"><h4>Please note</h4>
             <p>This document refers to the <strong>2.0</strong> version of Apache httpd, which <strong>is no longer maintained</strong>. Upgrade, and refer to the current version of httpd instead, documented at:</p>
         <ul><li><a href="http://httpd.apache.org/docs/current/">Current release version of Apache HTTP Server documentation</a></li></ul><p>You may follow <a href="http://httpd.apache.org/docs/current/mod/perchild.html">this link</a> to go to the current version of this document.</p></div><div id="preamble"><h1>Apache MPM perchild</h1>
 <div class="toplang">
 <p><span>Available Languages: </span><a href="../en/mod/perchild.html" title="English">&nbsp;en&nbsp;</a></p>
 </div>
 <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&#160;Identifier:</a></th><td>mpm_perchild_module</td></tr>
 <tr><th><a href="module-dict.html#SourceFile">Source&#160;File:</a></th><td>perchild.c</td></tr></table>
 <h3>Summary</h3>

     <div class="warning">
       This module is not functional.  Development of this module is not
       complete and is not currently active.  Do not use
       <code class="module"><a href="../mod/perchild.html">perchild</a></code> unless you are a programmer willing to
       help fix it.
     </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>
 </div>
 <div id="quickview"><h3 class="directives">Directives</h3>
 <ul id="toc">
 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#acceptmutex">AcceptMutex</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#assignuserid">AssignUserID</a></li>
 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#bs2000account">BS2000Account</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#enableexceptionhook">EnableExceptionHook</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/down.gif" /> <a href="#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/down.gif" /> <a href="#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#receivebuffersize">ReceiveBufferSize</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#serverlimit">ServerLimit</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#threadlimit">ThreadLimit</a></li>
 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#user">User</a></li>
 </ul>
 <h3>Topics</h3>
 <ul id="topics">
 <li><img alt="" src="../images/down.gif" /> <a href="#how-it-works">How it works</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="section">
 <h2><a name="how-it-works" id="how-it-works">How it works</a></h2>
     <p>A single control process launches the number of child processes
     indicated by the <code class="directive"><a href="#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="#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 <code class="program"><a href="../programs/suexec.html">suexec</a></code> 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>

     <h3><a name="user-ids" id="user-ids">Working with different user-IDs</a></h3>
       <p>The <code class="module"><a href="../mod/perchild.html">perchild</a></code> MPM adds the extra ability to
       specify that particular processes should serve requests under
       different user-IDs. These user-IDs can then be associated with
       specific virtual hosts. You have to use one <code class="directive"><a href="#childperuserid">ChildPerUserID</a></code> directive for
       every user/group combination you want to be run. Then you can tie
       particular virtual hosts to that user and group IDs.</p>

       <p>The following example runs 7 child processes. Two of them are run
       under <code>user1</code>/<code>group1</code>. The next four are run
       under <code>user2</code>/<code>group2</code> and the remaining
       process uses 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>
       of the main server:</p>

       <div class="example"><h3>Global config</h3><p><code>
         NumServers 7<br />
         ChildPerUserID user1 group1 2<br />
         ChildPerUserID user2 group2 4
       </code></p></div>

       <p>Using unbalanced numbers of processes as above is useful, if the
       particular virtual hosts produce different load. The assignment to
       the virtual hosts is easily done as in the example below. In
       conclusion with the example above the following assumes, that
       <code>server2</code> has to serve about twice of the hits of
       <code>server1</code>.</p>

       <div class="example"><h3>Example</h3><p><code>
         NameVirtualHost *<br />
         <br />
         &lt;VirtualHost *&gt;<br />
         <span class="indent">
           ServerName fallbackhost<br />
           # no assignment; use fallback<br />
         </span>
         &lt;/VirtualHost&gt;<br />
         <br />
         &lt;VirtualHost *&gt;<br />
         <span class="indent">
           ServerName server1<br />
           AssignUserID user1 group1<br />
         </span>
         &lt;/VirtualHost&gt;<br />
         <br />
         &lt;VirtualHost *&gt;<br />
         <span class="indent">
           ServerName server2<br />
           AssignUserID user2 group2<br />
         </span>
         &lt;/VirtualHost&gt;
       </code></p></div>

 </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>Tie a virtual host to a user and group ID</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 user/group combination. Requests
     addressed to the virtual host where this directive appears will be
     served by a process running with the specified user and group ID.</p>

     <p>The user and group ID has to be assigned to a number of children
     in the global server config using the <code class="directive"><a href="#childperuserid">ChildPerUserID</a></code> directive. See the section above for a
     <a href="#user-ids">configuration example</a>.</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>Specify user ID and group ID for a number of child
 processes</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, <var>num-children</var>, is the number of child
     processes to start with the specified user and group. It does
     <em>not</em> represent a specific child number. In order to use this
     directive, the server must be run initially as <code>root</code>.
     If you start the server as a non-root user, it will fail to change
     to the lesser privileged user.</p>

     <p>If the total number of child processes, found by totaling all of the
     third arguments to all <code class="directive">ChildPerUserID</code> directives
     in the config file, is less than <code class="directive"><a href="#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.
     See the section above for a <a href="#user-ids">configuration
     example</a>.</p>

     <div class="warning"><h3>Security</h3>
       <p>Don't set <var>user-id</var> (or <var>group-id</var>) to
       <code>root</code> unless you know exactly what you are doing, and
       what the dangers are.</p>
     </div>

 </div>
 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="directive-section"><h2><a name="MaxThreadsPerChild" id="MaxThreadsPerChild">MaxThreadsPerChild</a> <a name="maxthreadsperchild" id="maxthreadsperchild">Directive</a></h2>
 <table class="directive">
 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of threads per child process</td></tr>
 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxThreadsPerChild <var>number</var></code></td></tr>
 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxThreadsPerChild 64</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>This directive sets the maximum number of threads that will be
     created in each child process. To increase this value beyond its
     default, it is necessary to change the value of the <code class="directive"><a href="../mod/mpm_common.html#threadlimit">ThreadLimit</a></code> directive and stop and
     re-start the server.</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="NumServers" id="NumServers">NumServers</a> <a name="numservers" id="numservers">Directive</a></h2>
 <table class="directive">
 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Total number of children alive at the same time</td></tr>
 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NumServers <var>number</var></code></td></tr>
 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>NumServers 2</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>The <code class="directive">NumServers</code> directive determines the number
     of children alive at the same time. This number should be large enough to
     handle the requests for the entire site. To increase this value beyond the
     value of <code>8</code>, it is necessary to change the value of the
     <code class="directive"><a href="../mod/mpm_common.html#serverlimit">ServerLimit</a></code> directive and stop
     and re-start the server. See the section above for a <a href="#user-ids">configuration example</a>.</p>

 </div>
 </div>
 <div class="bottomlang">
 <p><span>Available Languages: </span><a href="../en/mod/perchild.html" title="English">&nbsp;en&nbsp;</a></p>
 </div><div id="footer">
 <p class="apache">Copyright 2013 The Apache Software Foundation.<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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	<title>perchild - Apache HTTP Server</title>
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	<p class="apache">Apache HTTP Server Version 2.0</p>
	<img alt="" src="../images/feather.gif" /></div>
	<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
	<div id="path">
	<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 2.0</a> > <a href="./">Modules</a></div>
	<div id="page-content">
	<div class="retired"><h4>Please note</h4>
	<p>This document refers to the <strong>2.0</strong> version of Apache httpd, which <strong>is no longer maintained</strong>. Upgrade, and refer to the current version of httpd instead, documented at:</p>
	<ul><li><a href="http://httpd.apache.org/docs/current/">Current release version of Apache HTTP Server documentation</a></li></ul><p>You may follow <a href="http://httpd.apache.org/docs/current/mod/perchild.html">this link</a> to go to the current version of this document.</p></div><div id="preamble"><h1>Apache MPM perchild</h1>
	<div class="toplang">
	<p><span>Available Languages: </span><a href="../en/mod/perchild.html" title="English"> en </a></p>
	</div>
	<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 Identifier:</a></th><td>mpm_perchild_module</td></tr>
	<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>perchild.c</td></tr></table>
	<h3>Summary</h3>

	<div class="warning">
	This module is not functional. Development of this module is not
	complete and is not currently active. Do not use
	<code class="module"><a href="../mod/perchild.html">perchild</a></code> unless you are a programmer willing to
	help fix it.
	</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>
	</div>
	<div id="quickview"><h3 class="directives">Directives</h3>
	<ul id="toc">
	<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#acceptmutex">AcceptMutex</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#assignuserid">AssignUserID</a></li>
	<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#bs2000account">BS2000Account</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#enableexceptionhook">EnableExceptionHook</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/down.gif" /> <a href="#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/down.gif" /> <a href="#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#receivebuffersize">ReceiveBufferSize</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#serverlimit">ServerLimit</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#threadlimit">ThreadLimit</a></li>
	<li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#user">User</a></li>
	</ul>
	<h3>Topics</h3>
	<ul id="topics">
	<li><img alt="" src="../images/down.gif" /> <a href="#how-it-works">How it works</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="section">
	<h2><a name="how-it-works" id="how-it-works">How it works</a></h2>
	<p>A single control process launches the number of child processes
	indicated by the <code class="directive"><a href="#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="#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 <code class="program"><a href="../programs/suexec.html">suexec</a></code> 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>

	<h3><a name="user-ids" id="user-ids">Working with different user-IDs</a></h3>
	<p>The <code class="module"><a href="../mod/perchild.html">perchild</a></code> MPM adds the extra ability to
	specify that particular processes should serve requests under
	different user-IDs. These user-IDs can then be associated with
	specific virtual hosts. You have to use one <code class="directive"><a href="#childperuserid">ChildPerUserID</a></code> directive for
	every user/group combination you want to be run. Then you can tie
	particular virtual hosts to that user and group IDs.</p>

	<p>The following example runs 7 child processes. Two of them are run
	under <code>user1</code>/<code>group1</code>. The next four are run
	under <code>user2</code>/<code>group2</code> and the remaining
	process uses 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>
	of the main server:</p>

	<div class="example"><h3>Global config</h3><p><code>
	NumServers 7<br />
	ChildPerUserID user1 group1 2<br />
	ChildPerUserID user2 group2 4
	</code></p></div>

	<p>Using unbalanced numbers of processes as above is useful, if the
	particular virtual hosts produce different load. The assignment to
	the virtual hosts is easily done as in the example below. In
	conclusion with the example above the following assumes, that
	<code>server2</code> has to serve about twice of the hits of
	<code>server1</code>.</p>

	<div class="example"><h3>Example</h3><p><code>
	NameVirtualHost *<br />
	<br />
	<VirtualHost *><br />
	<span class="indent">
	ServerName fallbackhost<br />
	# no assignment; use fallback<br />
	</span>
	</VirtualHost><br />
	<br />
	<VirtualHost *><br />
	<span class="indent">
	ServerName server1<br />
	AssignUserID user1 group1<br />
	</span>
	</VirtualHost><br />
	<br />
	<VirtualHost *><br />
	<span class="indent">
	ServerName server2<br />
	AssignUserID user2 group2<br />
	</span>
	</VirtualHost>
	</code></p></div>

	</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>Tie a virtual host to a user and group ID</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 user/group combination. Requests
	addressed to the virtual host where this directive appears will be
	served by a process running with the specified user and group ID.</p>

	<p>The user and group ID has to be assigned to a number of children
	in the global server config using the <code class="directive"><a href="#childperuserid">ChildPerUserID</a></code> directive. See the section above for a
	<a href="#user-ids">configuration example</a>.</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>Specify user ID and group ID for a number of child
	processes</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, <var>num-children</var>, is the number of child
	processes to start with the specified user and group. It does
	<em>not</em> represent a specific child number. In order to use this
	directive, the server must be run initially as <code>root</code>.
	If you start the server as a non-root user, it will fail to change
	to the lesser privileged user.</p>

	<p>If the total number of child processes, found by totaling all of the
	third arguments to all <code class="directive">ChildPerUserID</code> directives
	in the config file, is less than <code class="directive"><a href="#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.
	See the section above for a <a href="#user-ids">configuration
	example</a>.</p>

	<div class="warning"><h3>Security</h3>
	<p>Don't set <var>user-id</var> (or <var>group-id</var>) to
	<code>root</code> unless you know exactly what you are doing, and
	what the dangers are.</p>
	</div>

	</div>
	<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="directive-section"><h2><a name="MaxThreadsPerChild" id="MaxThreadsPerChild">MaxThreadsPerChild</a> <a name="maxthreadsperchild" id="maxthreadsperchild">Directive</a></h2>
	<table class="directive">
	<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of threads per child process</td></tr>
	<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxThreadsPerChild <var>number</var></code></td></tr>
	<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxThreadsPerChild 64</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>This directive sets the maximum number of threads that will be
	created in each child process. To increase this value beyond its
	default, it is necessary to change the value of the <code class="directive"><a href="../mod/mpm_common.html#threadlimit">ThreadLimit</a></code> directive and stop and
	re-start the server.</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="NumServers" id="NumServers">NumServers</a> <a name="numservers" id="numservers">Directive</a></h2>
	<table class="directive">
	<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Total number of children alive at the same time</td></tr>
	<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NumServers <var>number</var></code></td></tr>
	<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>NumServers 2</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>The <code class="directive">NumServers</code> directive determines the number
	of children alive at the same time. This number should be large enough to
	handle the requests for the entire site. To increase this value beyond the
	value of <code>8</code>, it is necessary to change the value of the
	<code class="directive"><a href="../mod/mpm_common.html#serverlimit">ServerLimit</a></code> directive and stop
	and re-start the server. See the section above for a <a href="#user-ids">configuration example</a>.</p>

	</div>
	</div>
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