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   8 <title>event - Apache HTTP Server</title>
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  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 2.3</p>
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  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 2.3</a> &gt; <a href="./">Modules</a></div>
  21 <div id="page-content">
  22 <div id="preamble"><h1>Apache MPM event</h1>
  23 <div class="toplang">
  24 <p><span>Available Languages: </span><a href="../en/mod/event.html" title="English">&nbsp;en&nbsp;</a></p>
  25 </div>
  26 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>An experimental variant of the standard <code class="module"><a href="../mod/worker.html">worker</a></code>
  27 MPM</td></tr>
  28 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>MPM</td></tr>
  29 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>mpm_event_module</td></tr>
  30 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>event.c</td></tr></table>
  31 <h3>Summary</h3>
  32
  33     <div class="warning"><h3>Warning</h3>
  34       <p>This MPM is experimental, so it may or may not work as
  35       expected.</p>
  36     </div>
  37
  38     <p>The <code class="module"><a href="../mod/event.html">event</a></code> Multi-Processing Module (MPM) is
  39     designed to allow more requests to be served simultaneously by
  40     passing off some processing work to supporting threads, freeing up
  41     the main threads to work on new requests.  It is based on the
  42     <code class="module"><a href="../mod/worker.html">worker</a></code> MPM, which implements a hybrid
  43     multi-process multi-threaded server.  Run-time configuration
  44     directives are identical to those provided by
  45     <code class="module"><a href="../mod/worker.html">worker</a></code>.</p>
  46
  47     <p>To use the <code class="module"><a href="../mod/event.html">event</a></code> MPM, add
  48       <code>--with-mpm=event</code> to the <code class="program"><a href="../programs/configure.html">configure</a></code>
  49       script's arguments when building the <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</p>
  50
  51 </div>
  52 <div id="quickview"><h3 class="directives">Directives</h3>
  53 <ul id="toc">
  54 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#acceptmutex">AcceptMutex</a></li>
  55 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#coredumpdirectory">CoreDumpDirectory</a></li>
  56 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#enableexceptionhook">EnableExceptionHook</a></li>
  57 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#group">Group</a></li>
  58 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#listen">Listen</a></li>
  59 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#listenbacklog">ListenBacklog</a></li>
  60 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#lockfile">LockFile</a></li>
  61 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxclients">MaxClients</a></li>
  62 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxmemfree">MaxMemFree</a></li>
  63 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></li>
  64 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxsparethreads">MaxSpareThreads</a></li>
  65 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#minsparethreads">MinSpareThreads</a></li>
  66 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#pidfile">PidFile</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#threadstacksize">ThreadStackSize</a></li>
  74 <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#user">User</a></li>
  75 </ul>
  76 <h3>Topics</h3>
  77 <ul id="topics">
  78 <li><img alt="" src="../images/down.gif" /> <a href="#how-it-works">How it Works</a></li>
  79 <li><img alt="" src="../images/down.gif" /> <a href="#requirements">Requirements</a></li>
  80 </ul><h3>See also</h3>
  81 <ul class="seealso">
  82 <li><a href="worker.html">The worker MPM</a></li>
  83 </ul></div>
  84 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
  85 <div class="section">
  86 <h2><a name="how-it-works" id="how-it-works">How it Works</a></h2>
  87     <p>This MPM tries to fix the 'keep alive problem' in HTTP. After a client
  88     completes the first request, the client can keep the connection
  89     open, and send further requests using the same socket. This can
  90     save signifigant overhead in creating TCP connections. However,
  91     Apache traditionally keeps an entire child process/thread waiting
  92     for data from the client, which brings its own disadvantages. To
  93     solve this problem, this MPM uses a dedicated thread to handle both
  94     the Listening sockets, and all sockets that are in a Keep Alive
  95     state.</p>
  96
  97     <p>The MPM assumes that the underlying <code>apr_pollset</code>
  98     implementation is reasonably threadsafe. This enables the MPM to
  99     avoid excessive high level locking, or having to wake up the listener
 100     thread in order to send it a keep-alive socket. This is currently
 101     only compatible with KQueue and EPoll.</p>
 102
 103 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 104 <div class="section">
 105 <h2><a name="requirements" id="requirements">Requirements</a></h2>
 106     <p>This MPM depends on <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a>'s atomic
 107     compare-and-swap operations for thread synchronization. If you are
 108     compiling for an x86 target and you don't need to support 386s, or
 109     you are compiling for a SPARC and you don't need to run on
 110     pre-UltraSPARC chips, add
 111     <code>--enable-nonportable-atomics=yes</code> to the
 112     <code class="program"><a href="../programs/configure.html">configure</a></code> script's arguments. This will cause
 113     APR to implement atomic operations using efficient opcodes not
 114     available in older CPUs.</p>
 115
 116     <p>This MPM does not perform well on older platforms which lack good
 117     threading, but the requirement for EPoll or KQueue makes this
 118     moot.</p>
 119
 120     <ul>
 121
 122       <li>To use this MPM on FreeBSD, FreeBSD 5.3 or higher is recommended.
 123       However, it is possible to run this MPM on FreeBSD 5.2.1, if you
 124       use <code>libkse</code> (see <code>man libmap.conf</code>).</li>
 125
 126       <li>For NetBSD, at least version 2.0 is recommended.</li>
 127
 128       <li>For Linux, a 2.6 kernel is recommended. It is also necessary to
 129       ensure that your version of <code>glibc</code> has been compiled
 130       with support for EPoll.</li>
 131
 132     </ul>
 133 </div>
 134 </div>
 135 <div class="bottomlang">
 136 <p><span>Available Languages: </span><a href="../en/mod/event.html" title="English">&nbsp;en&nbsp;</a></p>
 137 </div><div id="footer">
 138 <p class="apache">Copyright 2006 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>
 139 <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>
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