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| <title>event - Apache HTTP Server</title> |
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| <p class="apache">Apache HTTP Server Version 2.3</p> |
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| <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 2.3</a> > <a href="./">Modules</a></div> |
| <div id="page-content"> |
| <div id="preamble"><h1>Apache MPM event</h1> |
| <div class="toplang"> |
| <p><span>Available Languages: </span><a href="../en/mod/event.html" title="English"> en </a></p> |
| </div> |
| <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> |
| MPM</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_event_module</td></tr> |
| <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>event.c</td></tr></table> |
| <h3>Summary</h3> |
| |
| <div class="warning"><h3>Warning</h3> |
| <p>This MPM is experimental, so it may or may not work as |
| expected.</p> |
| </div> |
| |
| <p>The <code class="module"><a href="../mod/event.html">event</a></code> Multi-Processing Module (MPM) is |
| designed to allow more requests to be served simultaneously by |
| passing off some processing work to supporting threads, freeing up |
| the main threads to work on new requests. It is based on the |
| <code class="module"><a href="../mod/worker.html">worker</a></code> MPM, which implements a hybrid |
| multi-process multi-threaded server. Run-time configuration |
| directives are identical to those provided by |
| <code class="module"><a href="../mod/worker.html">worker</a></code>.</p> |
| |
| <p>To use the <code class="module"><a href="../mod/event.html">event</a></code> MPM, add |
| <code>--with-mpm=event</code> to the <code class="program"><a href="../programs/configure.html">configure</a></code> |
| script's arguments when building the <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</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/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#maxclients">MaxClients</a></li> |
| <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#maxmemfree">MaxMemFree</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/right.gif" /> <a href="mpm_common.html#minsparethreads">MinSpareThreads</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#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#startservers">StartServers</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#threadsperchild">ThreadsPerChild</a></li> |
| <li><img alt="" src="../images/right.gif" /> <a href="mpm_common.html#threadstacksize">ThreadStackSize</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> |
| <li><img alt="" src="../images/down.gif" /> <a href="#requirements">Requirements</a></li> |
| </ul><h3>See also</h3> |
| <ul class="seealso"> |
| <li><a href="worker.html">The worker MPM</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>This MPM tries to fix the 'keep alive problem' in HTTP. After a client |
| completes the first request, the client can keep the connection |
| open, and send further requests using the same socket. This can |
| save signifigant overhead in creating TCP connections. However, |
| Apache traditionally keeps an entire child process/thread waiting |
| for data from the client, which brings its own disadvantages. To |
| solve this problem, this MPM uses a dedicated thread to handle both |
| the Listening sockets, and all sockets that are in a Keep Alive |
| state.</p> |
| |
| <p>The MPM assumes that the underlying <code>apr_pollset</code> |
| implementation is reasonably threadsafe. This enables the MPM to |
| avoid excessive high level locking, or having to wake up the listener |
| thread in order to send it a keep-alive socket. This is currently |
| only compatible with KQueue and EPoll.</p> |
| |
| </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> |
| <div class="section"> |
| <h2><a name="requirements" id="requirements">Requirements</a></h2> |
| <p>This MPM depends on <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a>'s atomic |
| compare-and-swap operations for thread synchronization. If you are |
| compiling for an x86 target and you don't need to support 386s, or |
| you are compiling for a SPARC and you don't need to run on |
| pre-UltraSPARC chips, add |
| <code>--enable-nonportable-atomics=yes</code> to the |
| <code class="program"><a href="../programs/configure.html">configure</a></code> script's arguments. This will cause |
| APR to implement atomic operations using efficient opcodes not |
| available in older CPUs.</p> |
| |
| <p>This MPM does not perform well on older platforms which lack good |
| threading, but the requirement for EPoll or KQueue makes this |
| moot.</p> |
| |
| <ul> |
| |
| <li>To use this MPM on FreeBSD, FreeBSD 5.3 or higher is recommended. |
| However, it is possible to run this MPM on FreeBSD 5.2.1, if you |
| use <code>libkse</code> (see <code>man libmap.conf</code>).</li> |
| |
| <li>For NetBSD, at least version 2.0 is recommended.</li> |
| |
| <li>For Linux, a 2.6 kernel is recommended. It is also necessary to |
| ensure that your version of <code>glibc</code> has been compiled |
| with support for EPoll.</li> |
| |
| </ul> |
| </div> |
| </div> |
| <div class="bottomlang"> |
| <p><span>Available Languages: </span><a href="../en/mod/event.html" title="English"> en </a></p> |
| </div><div id="footer"> |
| <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> |
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