rubbos/app/httpd-2.0.64/docs/manual/mod/worker.html.en

   1 <?xml version="1.0" encoding="ISO-8859-1"?>
   2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
   3 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
   4         XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
   5               This file is generated from xml source: DO NOT EDIT
   6         XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
   7       -->
   8 <title>worker - Apache HTTP Server</title>
   9 <link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
  10 <link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
  11 <link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" />
  12 <link href="../images/favicon.ico" rel="shortcut icon" /></head>
  13 <body>
  14 <div id="page-header">
  15 <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>
  16 <p class="apache">Apache HTTP Server Version 2.0</p>
  17 <img alt="" src="../images/feather.gif" /></div>
  18 <div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="../images/left.gif" /></a></div>
  19 <div id="path">
  20 <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>
  21 <div id="page-content">
  22 <div id="preamble"><h1>Apache MPM worker</h1>
  23 <div class="toplang">
  24 <p><span>Available Languages: </span><a href="../de/mod/worker.html" hreflang="de" rel="alternate" title="Deutsch">&nbsp;de&nbsp;</a> |
  25 <a href="../en/mod/worker.html" title="English">&nbsp;en&nbsp;</a> |
  26 <a href="../es/mod/worker.html" hreflang="es" rel="alternate" title="Español">&nbsp;es&nbsp;</a> |
  27 <a href="../ja/mod/worker.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a> |
  28 <a href="../tr/mod/worker.html" hreflang="tr" rel="alternate" title="Türkçe">&nbsp;tr&nbsp;</a></p>
  29 </div>
  30 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Multi-Processing Module implementing a hybrid
  31     multi-threaded multi-process web server</td></tr>
  32 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>MPM</td></tr>
  33 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>mpm_worker_module</td></tr>
  34 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>worker.c</td></tr></table>
  35 <h3>Summary</h3>
  36
  37     <p>This Multi-Processing Module (MPM) implements a hybrid
  38     multi-process multi-threaded server.  By using threads to serve
  39     requests, it is able to serve a large number of requests with
  40     less system resources than a process-based server.  Yet it
  41     retains much of the stability of a process-based server by
  42     keeping multiple processes available, each with many threads.</p>
  43
  44     <p>The most important directives used to control this MPM are
  45     <code class="directive"><a href="../mod/mpm_common.html#threadsperchild">ThreadsPerChild</a></code>, which
  46     controls the number of threads deployed by each child process and
  47     <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code>, which
  48     controls the maximum total number of threads that may be
  49     launched.</p>
  50 </div>
  51 <div id="quickview"><h3 class="directives">Directives</h3>
  52 <ul id="toc">
  53 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#acceptmutex">AcceptMutex</a></li>
  54 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#coredumpdirectory">CoreDumpDirectory</a></li>
  55 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#enableexceptionhook">EnableExceptionHook</a></li>
  56 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#group">Group</a></li>
  57 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#listen">Listen</a></li>
  58 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#listenbacklog">ListenBacklog</a></li>
  59 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#lockfile">LockFile</a></li>
  60 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxclients">MaxClients</a></li>
  61 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxmemfree">MaxMemFree</a></li>
  62 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></li>
  63 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxsparethreads">MaxSpareThreads</a></li>
  64 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#minsparethreads">MinSpareThreads</a></li>
  65 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#pidfile">PidFile</a></li>
  66 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#receivebuffersize">ReceiveBufferSize</a></li>
  67 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#scoreboardfile">ScoreBoardFile</a></li>
  68 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#sendbuffersize">SendBufferSize</a></li>
  69 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#serverlimit">ServerLimit</a></li>
  70 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#startservers">StartServers</a></li>
  71 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#threadlimit">ThreadLimit</a></li>
  72 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#threadsperchild">ThreadsPerChild</a></li>
  73 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#user">User</a></li>
  74 </ul>
  75 <h3>Topics</h3>
  76 <ul id="topics">
  77 <li><img alt="" src="../images/down.gif" /> <a href="#how-it-works">How it Works</a></li>
  78 </ul><h3>See also</h3>
  79 <ul class="seealso">
  80 <li><a href="../bind.html">Setting which addresses and ports Apache
  81 uses</a></li>
  82 </ul></div>
  83 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
  84 <div class="section">
  85 <h2><a name="how-it-works" id="how-it-works">How it Works</a></h2>
  86     <p>A single control process (the parent) is responsible for launching
  87     child processes. Each child process creates a fixed number of server
  88     threads as specified in the <code class="directive"><a href="../mod/mpm_common.html#threadsperchild">ThreadsPerChild</a></code> directive, as well
  89     as a listener thread which listens for connections and passes them
  90     to a server thread for processing when they arrive.</p>
  91
  92     <p>Apache always tries to maintain a pool of <dfn>spare</dfn> or
  93     idle server threads, which stand ready to serve incoming
  94     requests. In this way, clients do not need to wait for a new
  95     threads or processes to be created before their requests can be
  96     served. The number of processes that will initially launched is
  97     set by the <code class="directive"><a href="../mod/mpm_common.html#startservers">StartServers</a></code>
  98     directive. Then during operation, Apache assesses the total number
  99     of idle threads in all processes, and forks or kills processes to
 100     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
 101     process is very self-regulating, it is rarely necessary to modify
 102     these directives from their default values. The maximum number of
 103     clients that may be served simultaneously (i.e., the maximum total
 104     number of threads in all processes) is determined by the
 105     <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code> directive.
 106     The maximum number of active child processes is determined by
 107     the <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code>
 108     directive divided by the <code class="directive"><a href="../mod/mpm_common.html#&#10;    threadsperchild">
 109     ThreadsPerChild</a></code> directive.</p>
 110
 111     <p>Two directives set hard limits on the number of active child
 112     processes and the number of server threads in a child process,
 113     and can only be changed by fully stopping the server and then
 114     starting it again.  <code class="directive"><a href="../mod/mpm_common.html#serverlimit&#10;    ">ServerLimit
 115     </a></code> is a hard limit on the number of active child
 116     processes, and must be greater than or equal to the
 117     <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code>
 118     directive divided by the <code class="directive"><a href="../mod/mpm_common.html#&#10;    threadsperchild">
 119     ThreadsPerChild</a></code> directive.
 120     <code class="directive"><a href="../mod/mpm_common.html#threadlimit">ThreadLimit</a></code> is a hard
 121     limit of the number of server threads, and must be greater than
 122     or equal to the <code class="directive"><a href="../mod/mpm_common.html#threadsperchild">ThreadsPerChild</a></code> directive.  If
 123     non-default values are specified for these directives, they
 124     should appear before other <code class="module"><a href="../mod/worker.html">worker</a></code> directives.</p>
 125
 126     <p>In addition to the set of active child processes, there may
 127     be additional child processes which are terminating but where at
 128     least one server thread is still handling an existing client
 129     connection.  Up to <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code> terminating processes
 130     may be present, though the actual number can be expected to be
 131     much smaller.  This behavior can be avoided by disabling the
 132     termination of individual child processes, which is achieved by
 133     the following:</p>
 134
 135     <ul>
 136       <li>set the value of <code class="directive"><a href="../mod/mpm_common.html#&#10;      maxrequestsperchild">
 137       MaxRequestsPerChild</a></code> to zero</li>
 138
 139       <li>set the value of <code class="directive"><a href="../mod/mpm_common.html#&#10;      maxsparethreads">
 140       MaxSpareThreads</a></code> to the same value as
 141       <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code></li>
 142     </ul>
 143
 144     <p>A typical configuration of the process-thread controls in
 145     the <code class="module"><a href="../mod/worker.html">worker</a></code> MPM could look as follows:</p>
 146
 147     <div class="example"><p><code>
 148       ServerLimit         16<br />
 149       StartServers         2<br />
 150       MaxClients         150<br />
 151       MinSpareThreads     25<br />
 152       MaxSpareThreads     75<br />
 153       ThreadsPerChild     25
 154     </code></p></div>
 155
 156     <p>While the parent process is usually started as <code>root</code>
 157     under Unix in order to bind to port 80, the child processes and threads
 158     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
 159     the privileges of the Apache child processes. The child processes
 160     must be able to read all the content that will be served, but
 161     should have as few privileges beyond that as possible. In
 162     addition, unless <code class="program"><a href="../programs/suexec.html">suexec</a></code> is used,
 163     these directives also set the privileges which will be inherited
 164     by CGI scripts.</p>
 165
 166     <p><code class="directive"><a href="../mod/mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></code>
 167     controls how frequently the server recycles processes by killing
 168     old ones and launching new ones.</p>
 169 </div>
 170 </div>
 171 <div class="bottomlang">
 172 <p><span>Available Languages: </span><a href="../de/mod/worker.html" hreflang="de" rel="alternate" title="Deutsch">&nbsp;de&nbsp;</a> |
 173 <a href="../en/mod/worker.html" title="English">&nbsp;en&nbsp;</a> |
 174 <a href="../es/mod/worker.html" hreflang="es" rel="alternate" title="Español">&nbsp;es&nbsp;</a> |
 175 <a href="../ja/mod/worker.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a> |
 176 <a href="../tr/mod/worker.html" hreflang="tr" rel="alternate" title="Türkçe">&nbsp;tr&nbsp;</a></p>
 177 </div><div id="footer">
 178 <p class="apache">Copyright 2009 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>
 179 <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>
 180 </body></html>