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183 lines
7.1 KiB
HTML
183 lines
7.1 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta name="generator" content="HTML Tidy, see www.w3.org" />
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<title>Apache MPM perchild</title>
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</head>
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<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
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<body bgcolor="#FFFFFF" text="#000000" link="#0000FF"
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vlink="#000080" alink="#FF0000">
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<!--#include virtual="header.html" -->
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<h1 align="CENTER">Multi-Processing Module perchild</h1>
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<blockquote><strong>
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This MPM does not currently work on most platforms. Work is ongoing to
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make it functional.
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</strong></blockquote>
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<p>This Multi-Processing Module allows for daemon processes
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serving requests to be assigned a variety of different
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userids.</p>
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<p><a href="module-dict.html#Status"
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rel="Help"><strong>Status:</strong></a> MPM<br />
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<a href="module-dict.html#SourceFile"
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rel="Help"><strong>Source File:</strong></a> perchild.c<br />
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<a href="module-dict.html#ModuleIdentifier"
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rel="Help"><strong>Module Identifier:</strong></a>
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mpm_perchild_module</p>
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<h2>Summary</h2>
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<p>This Multi-Processing Module (MPM) implements a hybrid
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multi-process, multi-threaded web server. A fixed number of
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processes create threads to handle requests. Fluctuations in
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load are handled by increasing or decreasing the number of
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threads in each process.</p>
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<p>A single control process launches the number of child
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processes indicated by the <code>NumServers</code> directive at
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server startup. Each child process creates threads as specified
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in the <code>StartThreads</code> directive. The individual
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threads then listen for connections and serve them when they
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arrive.</p>
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<p>Apache always tries to maintain a pool of <em>spare</em> or
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idle server threads, which stand ready to serve incoming
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requests. In this way, clients do not need to wait for new
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threads to be created. For each child process, Apache assesses
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the number of idle threads and creates or destroys threads to
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keep this number within the boundaries specified by
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<code>MinSpareThreads</code> and <code>MaxSpareThreads</code>.
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Since this process is very self-regulating, it is rarely
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necessary to modify these directives from their default values.
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The maximum number of clients that may be served simultaneously
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is determined by multiplying the number of server processes
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that will be created (<code>NumServers</code>) by the maximum
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number of threads created in each process
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(<code>MaxThreadsPerChild</code>).</p>
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<p>While the parent process is usually started as root under
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Unix in order to bind to port 80, the child processes and
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threads are launched by Apache as a less-privileged user. The
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<code>User</code> and <code>Group</code> directives are used to
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set the privileges of the Apache child processes. The child
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processes must be able to read all the content that will be
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served, but should have as few privileges beyond that as
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possible. In addition, unless <a
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href="../suexec.html">suexec</a> is used, these directives also
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set the privileges which will be inherited by CGI scripts.</p>
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<p><code>MaxRequestsPerChild</code> controls how frequently the
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server recycles processes by killing old ones and launching new
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ones.</p>
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<p>See also: <a href="../bind.html">Setting which addresses and
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ports Apache uses</a>.</p>
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<p>In addition it adds the extra ability to specify that
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specific processes should serve requests under different
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userids. These processes can then be associated with specific
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virtual hosts.</p>
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<!-- XXX: This desperately needs more explanation. -->
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<h2>Directives</h2>
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<ul>
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<li><a href="#assignuserid">AssignUserID</a></li>
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<li><a href="#childperuserid">ChildPerUserID</a></li>
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<li><a
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href="mpm_common.html#coredumpdirectory">CoreDumpDirectory</a></li>
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<li><a href="mpm_common.html#group">Group</a></li>
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<li><a href="mpm_common.html#pidfile">PidFile</a></li>
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<li><a href="mpm_common.html#listen">Listen</a></li>
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<li><a
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href="mpm_common.html#listenbacklog">ListenBacklog</a></li>
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<li><a href="mpm_common.html#lockfile">LockFile</a></li>
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<li><a
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href="mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></li>
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<li><a
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href="mpm_common.html#maxsparethreads">MaxSpareThreads</a></li>
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<li><a
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href="mpm_common.html#maxthreadsperchild">MaxThreadsPerChild</a></li>
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<li><a
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href="mpm_common.html#minsparethreads">MinSpareThreads</a></li>
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<li><a href="mpm_common.html#numservers">NumServers</a></li>
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<li><a
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href="mpm_common.html#scoreboardfile">ScoreBoardFile</a></li>
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<li><a
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href="mpm_common.html#sendbuffersize">SendBufferSize</a></li>
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<li><a
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href="mpm_common.html#startthreads">StartThreads</a></li>
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<li><a href="mpm_common.html#user">User</a></li>
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</ul>
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<hr />
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<h2><a id="assignuserid" name="assignuserid">AssignUserID
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directive</a></h2>
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<p><a href="directive-dict.html#Syntax"
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rel="Help"><strong>Syntax:</strong></a>AssignUserID <em>user_id</em> <em>group_id</em><br />
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<a href="directive-dict.html#Default"
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rel="Help"><strong>Default:</strong></a><br />
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<a href="directive-dict.html#Context"
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rel="Help"><strong>Context:</strong></a> virtual host<br />
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<a href="directive-dict.html#Status"
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rel="Help"><strong>Status:</strong></a> MPM<br />
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<a href="directive-dict.html#Module"
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rel="Help"><strong>Module:</strong></a> perchild</p>
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<p>Tie a virtual host to a specific child process. Requests addressed to
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the virtual host where this directive appears will be served by the process
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running with the specified user and group id.</p>
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<hr />
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<h2><a id="childperuserid" name="childperuserid">ChildPerUserID
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directive</a></h2>
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<p><a href="directive-dict.html#Syntax"
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rel="Help"><strong>Syntax:</strong></a>ChildPerUserID <em>user_id</em>
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<em>group_id</em> <em>child_id</em><br />
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<a href="directive-dict.html#Default"
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rel="Help"><strong>Default:</strong></a><br />
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<a href="directive-dict.html#Context"
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rel="Help"><strong>Context:</strong></a> server config<br />
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<a href="directive-dict.html#Status"
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rel="Help"><strong>Status:</strong></a> MPM<br />
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<a href="directive-dict.html#Module"
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rel="Help"><strong>Module:</strong></a> perchild</p>
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<p>Specify a user id and group id for a specific child process. The number of
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children if set by the <a href="mpm_common.html#numservers">NumServers</a>
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directive. For example, the default value for <a
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href="mpm_common.html#numservers">NumServers</a> is 5 and that means
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children ids 1,2,3,4 and 5 are available for assigment. If a child does not
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have an associated ChildPerUserID, it inherits the <a
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href="mpm_common.html#user">User</a> and <a
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href="mpm_common.html#group">Group</a> settings from the main server </p>
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<!--#include virtual="footer.html" -->
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</body>
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</html>
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