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956 lines
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<title>mpm_common - Apache HTTP Server Version 2.5</title>
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<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
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<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
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<link href="../images/favicon.ico" rel="shortcut icon" /></head>
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<body>
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<div id="page-header">
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<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
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<p class="apache">Apache HTTP Server Version 2.5</p>
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<img alt="" src="../images/feather.png" /></div>
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<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
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<div id="path">
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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 2.5</a> > <a href="./">Modules</a></div>
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<div id="page-content">
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<div id="preamble"><h1>Apache MPM Common Directives</h1>
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<div class="toplang">
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<p><span>Available Languages: </span><a href="../de/mod/mpm_common.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
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<a href="../en/mod/mpm_common.html" title="English"> en </a> |
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<a href="../fr/mod/mpm_common.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
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<a href="../ja/mod/mpm_common.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
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<a href="../tr/mod/mpm_common.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
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</div>
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<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>A collection of directives that are implemented by
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more than one multi-processing module (MPM)</td></tr>
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<tr><th><a href="module-dict.html#Status">Status:</a></th><td>MPM</td></tr></table>
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</div>
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<div id="quickview"><h3 class="directives">Directives</h3>
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<ul id="toc">
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<li><img alt="" src="../images/down.gif" /> <a href="#accepterrorsnonfatal">AcceptErrorsNonFatal</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#coredumpdirectory">CoreDumpDirectory</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#enableexceptionhook">EnableExceptionHook</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#gracefulshutdowntimeout">GracefulShutdownTimeout</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#listen">Listen</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#listenbacklog">ListenBackLog</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#listencoresbucketsratio">ListenCoresBucketsRatio</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#maxconnectionsperchild">MaxConnectionsPerChild</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#maxmemfree">MaxMemFree</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#maxrequestworkers">MaxRequestWorkers</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#maxsparethreads">MaxSpareThreads</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#minsparethreads">MinSpareThreads</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#pidfile">PidFile</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#receivebuffersize">ReceiveBufferSize</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#scoreboardfile">ScoreBoardFile</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#sendbuffersize">SendBufferSize</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#serverlimit">ServerLimit</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#startservers">StartServers</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#startthreads">StartThreads</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#threadlimit">ThreadLimit</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#threadsperchild">ThreadsPerChild</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#threadstacksize">ThreadStackSize</a></li>
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</ul>
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<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=mpm_common">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=mpm_common">Report a bug</a></li></ul><h3>See also</h3>
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<ul class="seealso">
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<li><a href="#comments_section">Comments</a></li></ul></div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="directive-section"><h2><a name="AcceptErrorsNonFatal" id="AcceptErrorsNonFatal">AcceptErrorsNonFatal</a> <a name="accepterrorsnonfatal" id="accepterrorsnonfatal">Directive</a> <a title="Permanent link" href="#accepterrorsnonfatal" class="permalink">¶</a></h2>
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<table class="directive">
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<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Treat some errors accepting a new connection as non-fatal
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to the httpd process.</td></tr>
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<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptErrorsNonFatal ON</code></td></tr>
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<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>OFF (ECONNREFUSED, ECONNABORTED, ECONNRESET cause the process to
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exit)</code></td></tr>
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<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
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<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
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<tr><th><a href="directive-dict.html#Module">Module:</a></th><td><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code></td></tr>
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<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5.1 and later</td></tr>
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</table>
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<p>The <code class="directive">AcceptErrorsNonFatal</code> alters the servers
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behavior under some rare errors that may occur while accepting a new
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client connection. By default, the child process handling a request
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will gracefully exit when nearly any socket error occurs during the
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accept() system call. This is to ensure a potentially unhealthy
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child process does not try to take on more new connections.</p>
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<p>With <code class="directive">AcceptErrorsNonFatal</code> set to "ON",
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the process will <em>not</em> begin to exit if the accept() error is
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ECONNREFUSED, ECONNABORTED, or ECONNRESET.</p>
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<div class="note">Some third-party firwewall software components may inject errors
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into accept() processing, using return codes not specified by the
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operating system.</div>
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</div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="directive-section"><h2><a name="CoreDumpDirectory" id="CoreDumpDirectory">CoreDumpDirectory</a> <a name="coredumpdirectory" id="coredumpdirectory">Directive</a> <a title="Permanent link" href="#coredumpdirectory" class="permalink">¶</a></h2>
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<table class="directive">
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<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory where Apache HTTP Server attempts to
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switch before dumping core</td></tr>
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<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CoreDumpDirectory <var>directory</var></code></td></tr>
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<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for the default setting</code></td></tr>
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<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
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<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
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<tr><th><a href="directive-dict.html#Module">Module:</a></th><td><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code></td></tr>
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</table>
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<p>This controls the directory to which Apache httpd attempts to
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switch before dumping core. If your operating system is configured to
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create core files in the working directory of the crashing process,
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<code class="directive">CoreDumpDirectory</code> is necessary to change working
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directory from the default <code class="directive"><a href="../mod/core.html#serverroot">ServerRoot</a></code>
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directory, which should not be writable by the user the server runs as.</p>
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<p>If you want a core dump for debugging, you can use this directive to
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place it in a different location. This directive has no effect if your
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operating system is not configured to write core files to the working directory
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of the crashing processes.</p>
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<div class="warning">
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<h3>Security note for Linux systems</h3>
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<p>Using this directive on Linux may allow other processes on
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the system (if running with similar privileges, such as CGI
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scripts) to attach to httpd children via the <code>ptrace</code>
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system call. This may make weaken the protection from certain
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security attacks. It is not recommended to use this directive
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on production systems.</p>
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</div>
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<div class="note"><h3>Core Dumps on Linux</h3>
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<p>If Apache httpd starts as root and switches to another user, the
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Linux kernel <em>disables</em> core dumps even if the directory is
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writable for the process. Apache httpd (2.0.46 and later) reenables core dumps
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on Linux 2.4 and beyond, but only if you explicitly configure a <code class="directive">CoreDumpDirectory</code>.</p>
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</div>
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<div class="note">
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<h3>Core Dumps on BSD</h3>
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<p>To enable core-dumping of suid-executables on BSD-systems (such
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as FreeBSD), set <code>kern.sugid_coredump</code> to 1.
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</p>
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</div>
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<div class="note"><h3>Specific signals</h3>
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<p><code class="directive">CoreDumpDirectory</code> processing only occurs for
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a select set of fatal signals: SIGFPE, SIGILL, SIGABORT,
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SIGSEGV, and SIGBUS.</p>
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<p>On some operating systems, SIGQUIT also results in a core dump but
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does not go through <code class="directive">CoreDumpDirectory</code> or
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<code class="directive">EnableExceptionHook</code> processing, so the core
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location is dictated entirely by the operating system.</p>
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</div>
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</div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="directive-section"><h2><a name="EnableExceptionHook" id="EnableExceptionHook">EnableExceptionHook</a> <a name="enableexceptionhook" id="enableexceptionhook">Directive</a> <a title="Permanent link" href="#enableexceptionhook" class="permalink">¶</a></h2>
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<table class="directive">
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<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables a hook that runs exception handlers
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after a crash</td></tr>
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<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableExceptionHook On|Off</code></td></tr>
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<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableExceptionHook Off</code></td></tr>
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<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
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<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
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<tr><th><a href="directive-dict.html#Module">Module:</a></th><td><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code></td></tr>
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</table>
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<p>For safety reasons this directive is only available if the server was
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configured with the <code>--enable-exception-hook</code> option. It
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enables a hook that allows external modules to plug in and do something
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after a child crashed.</p>
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<p>There are already two modules, <code>mod_whatkilledus</code> and
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<code>mod_backtrace</code> that make use of this hook. Please have a
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look at Jeff Trawick's <a href="https://emptyhammock.com/projects/httpd/diag/">EnableExceptionHook site</a> for more information about these.</p>
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</div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="directive-section"><h2><a name="GracefulShutdownTimeout" id="GracefulShutdownTimeout">GracefulShutdownTimeout</a> <a name="gracefulshutdowntimeout" id="gracefulshutdowntimeout">Directive</a> <a title="Permanent link" href="#gracefulshutdowntimeout" class="permalink">¶</a></h2>
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<table class="directive">
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<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Specify a timeout after which a gracefully shutdown server
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will exit.</td></tr>
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<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>GracefulShutdownTimeout <var>seconds</var></code></td></tr>
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<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>GracefulShutdownTimeout 0</code></td></tr>
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<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
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<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
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<tr><th><a href="directive-dict.html#Module">Module:</a></th><td><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code></td></tr>
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</table>
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<p>The <code class="directive">GracefulShutdownTimeout</code> specifies
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how many seconds after receiving a "graceful-stop" signal, a
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server should continue to run, handling the existing connections.</p>
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<p>Setting this value to zero means that the server will wait
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indefinitely until all remaining requests have been fully served.</p>
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</div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="directive-section"><h2><a name="Listen" id="Listen">Listen</a> <a name="listen" id="listen">Directive</a> <a title="Permanent link" href="#listen" class="permalink">¶</a></h2>
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<table class="directive">
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<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>IP addresses and ports that the server
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listens to</td></tr>
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<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Listen [<var>IP-address</var>:]<var>portnumber</var> [<var>protocol</var>] [options=<var>flag</var>[,<var>flag..</var>]]</code></td></tr>
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<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
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<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
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<tr><th><a href="directive-dict.html#Module">Module:</a></th><td><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
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<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The optional <code>options=</code> argument is available in httpd 2.5.1 and later.</td></tr>
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</table>
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<p>The <code class="directive">Listen</code> directive instructs Apache httpd to
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listen to only specific IP addresses or ports; by default it
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responds to requests on all IP interfaces. <code class="directive">Listen</code>
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is now a required directive. If it is not in the config file, the
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server will fail to start. This is a change from previous versions
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of Apache httpd.</p>
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<p>The <code class="directive">Listen</code> directive tells the server to
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accept incoming requests on the specified port or address-and-port
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combination. If only a port number is specified, the server listens to
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the given port on all interfaces. If an IP address is given as well
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as a port, the server will listen on the given port and
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interface.</p>
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<p>Multiple <code class="directive">Listen</code> directives may be used to
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specify a number of addresses and ports to listen to. The server will
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respond to requests from any of the listed addresses and ports.</p>
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<p>For example, to make the server accept connections on both
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port 80 and port 8000, use:</p>
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<pre class="prettyprint lang-config">Listen 80
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Listen 8000</pre>
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|
|
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<p>To make the server accept connections on two specified
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interfaces and port numbers, use </p>
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<pre class="prettyprint lang-config">Listen 192.170.2.1:80
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Listen 192.170.2.5:8000</pre>
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|
|
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<p>IPv6 addresses must be surrounded in square brackets, as in the
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following example:</p>
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<pre class="prettyprint lang-config">Listen [2001:db8::a00:20ff:fea7:ccea]:80</pre>
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<p>In httpd 2.5.1 and later, if built against APR 1.7.0 or later,
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scoped (or "zoned") literal IPv6 addresses are accepted in the
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<code class="directive">Listen</code> directive, such as the following
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example.</p>
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<pre class="prettyprint lang-config">Listen [fe80::4bfe:88aa:5d42:64d0%eth2]:8081</pre>
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<p>The optional <var>protocol</var> argument is not required for most
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configurations. If not specified, <code>https</code> is the default for
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port 443 and <code>http</code> the default for all other ports. The
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protocol is used to determine which module should handle a request, and
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to apply protocol specific optimizations with the
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<code class="directive"><a href="../mod/core.html#acceptfilter">AcceptFilter</a></code> directive.</p>
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<p>You only need to set the protocol if you are running on non-standard
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ports. For example, running an <code>https</code> site on port 8443:</p>
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<pre class="prettyprint lang-config">Listen 192.170.2.1:8443 https</pre>
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<p>The optional <var>options=flag,flag...</var> argument can be
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used to enable certain socket options for the listening port.
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These options are not required for most configurations and should
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be used with care. Availability of each flag varies across
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operating systems. The available <em>flag</em>s are:</p>
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<ul>
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<li><code>freebind</code>: The <code>IP_FREEBIND</code> socket
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option is enabled, allowing a Listen directive to be used for an
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address which is not (yet) available on the system. (Linux
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only)</li>
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<li><code>reuseport</code>: The <code>SO_REUSEPORT</code> socket
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option is enabled, allowing a Listen directive to bind to a port
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which may already be in use by another process.</li>
|
|
|
|
<li><code>v6only</code>: The <code>IPV6_V6ONLY</code> socket
|
|
option is enabled, allowing a Listen directive to bind to an
|
|
IPv6 address without also accepting connections via IPv4, or
|
|
conflicting with a Listen directive using an IPv4 address bound
|
|
to the same port. (If the server is built with IPv4-mapped
|
|
addresses <em>disabled</em>, this is the default behaviour and
|
|
this option has no effect.)</li>
|
|
</ul>
|
|
|
|
<div class="note"><h3>Error condition</h3>
|
|
Multiple <code class="directive">Listen</code> directives for the same IP
|
|
address and port will result in an <code>Address already in use</code>
|
|
error message.
|
|
</div>
|
|
|
|
|
|
<h3>See also</h3>
|
|
<ul>
|
|
<li><a href="../dns-caveats.html">DNS Issues</a></li>
|
|
<li><a href="../bind.html">Setting which addresses and ports Apache HTTP Server
|
|
uses</a></li>
|
|
<li><a href="http://wiki.apache.org/httpd/CouldNotBindToAddress">Further
|
|
discussion of the <code>Address already in use</code> error message,
|
|
including other causes.</a></li>
|
|
</ul>
|
|
</div>
|
|
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
|
<div class="directive-section"><h2><a name="ListenBackLog" id="ListenBackLog">ListenBackLog</a> <a name="listenbacklog" id="listenbacklog">Directive</a> <a title="Permanent link" href="#listenbacklog" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum length of the queue of pending connections</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ListenBackLog <var>backlog</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ListenBackLog 511</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
|
|
</table>
|
|
<p>The maximum length of the queue of pending connections.
|
|
Generally no tuning is needed or desired; however, on some
|
|
systems, it is desirable to increase this when under a TCP SYN
|
|
flood attack. See the backlog parameter to the
|
|
<code>listen(2)</code> system call.</p>
|
|
|
|
<p>This will often be limited to a smaller number by the
|
|
operating system. This varies from OS to OS. Also note that
|
|
many OSes do not use exactly what is specified as the backlog,
|
|
but use a number based on (but normally larger than) what is
|
|
set.</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="ListenCoresBucketsRatio" id="ListenCoresBucketsRatio">ListenCoresBucketsRatio</a> <a name="listencoresbucketsratio" id="listencoresbucketsratio">Directive</a> <a title="Permanent link" href="#listencoresbucketsratio" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Ratio between the number of CPU cores (online) and the number of
|
|
listeners' buckets</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ListenCoresBucketsRatio <var>ratio</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ListenCoresBucketsRatio 0 (disabled)</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.4.17, with a kernel supporting
|
|
the socket option <code>SO_REUSEPORT</code> and distributing new connections
|
|
evenly across listening processes' (or threads') sockets using it (eg. Linux
|
|
3.9 and later, but not the current implementations of <code>SO_REUSEPORT</code>
|
|
in *BSDs.</td></tr>
|
|
</table>
|
|
<p>A <var>ratio</var> between the number of (online) CPU cores and the
|
|
number of listeners' buckets can be used to make Apache HTTP Server create
|
|
<code>num_cpu_cores / ratio</code> listening buckets, each containing its
|
|
own <code class="directive"><a href="#listen">Listen</a></code>-ing socket(s) on the same port(s), and
|
|
then make each child handle a single bucket (with round-robin distribution
|
|
of the buckets at children creation time).</p>
|
|
|
|
<div class="note"><h3>Meaning of "online" CPU core</h3>
|
|
<p>On Linux (and also BSD) a CPU core can be turned on/off if
|
|
<a href="https://www.kernel.org/doc/Documentation/cpu-hotplug.txt">Hotplug</a>
|
|
is configured, therefore <code class="directive">ListenCoresBucketsRatio</code> needs to
|
|
take this parameter into account while calculating the number of buckets to create.</p>
|
|
</div>
|
|
|
|
<p><code class="directive">ListenCoresBucketsRatio</code> can improve the
|
|
scalability when accepting new connections is/becomes the bottleneck.
|
|
On systems with a large number of CPU cores, enabling this feature has
|
|
been tested to show significant performances improvement and shorter
|
|
responses time.</p>
|
|
|
|
<p>There must be at least twice the number of CPU cores than the
|
|
configured <var>ratio</var> for this to be active. The recommended
|
|
<var>ratio</var> is <code>8</code>, hence at least <code>16</code>
|
|
cores should be available at runtime when this value is used.
|
|
The right <var>ratio</var> to obtain maximum performance needs to be calculated
|
|
for each target system, testing multiple values and observing the variations in your
|
|
key performance metrics.</p>
|
|
|
|
<p>This directive influences the calculation of the
|
|
<code class="directive"><a href="#minsparethreads">MinSpareThreads</a></code> and
|
|
<code class="directive"><a href="#maxsparethreads">MaxSpareThreads</a></code> lower bound values.
|
|
The number of children processes needs to be a multiple of the number
|
|
of buckets to optimally accept connections.</p>
|
|
|
|
<div class="note">
|
|
<h3>Multiple <code class="directive">Listen</code>ers or Apache HTTP servers on
|
|
the same IP address and port</h3>
|
|
<p>Setting the <code>SO_REUSEPORT</code> option on the listening socket(s)
|
|
consequently allows multiple processes (sharing the same <code>EUID</code>,
|
|
e.g. <code>root</code>) to bind to the the same IP address and port,
|
|
without the binding error raised by the system in the usual case.</p>
|
|
<p>This also means that multiple instances of Apache httpd configured on a
|
|
same <code>IP:port</code> and with a positive <code class="directive">ListenCoresBucketsRatio</code>
|
|
would start without an error too, and then run with incoming connections
|
|
evenly distributed across both instances (this is NOT a recommendation or
|
|
a sensible usage in any case, but just a notice that it would prevent such
|
|
possible issues to be detected).</p>
|
|
<p>Within the same instance, Apache httpd will check and fail to start if
|
|
multiple <code class="directive">Listen</code> directives on the exact same IP (or
|
|
hostname) and port are configured, thus avoiding the creation of some
|
|
duplicated buckets which would be useless and kill performances. However
|
|
it can't (and won't try harder to) catch all the possible overlapping cases
|
|
(like a hostname resolving to an IP used elsewhere).</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="MaxConnectionsPerChild" id="MaxConnectionsPerChild">MaxConnectionsPerChild</a> <a name="maxconnectionsperchild" id="maxconnectionsperchild">Directive</a> <a title="Permanent link" href="#maxconnectionsperchild" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limit on the number of connections that an individual child server
|
|
will handle during its life</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxConnectionsPerChild <var>number</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxConnectionsPerChild 0</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available Apache HTTP Server 2.3.9 and later. The old name
|
|
<code>MaxRequestsPerChild</code> is still supported.</td></tr>
|
|
</table>
|
|
<p>The <code class="directive">MaxConnectionsPerChild</code> directive sets
|
|
the limit on the number of connections that an individual child
|
|
server process will handle. After
|
|
<code class="directive">MaxConnectionsPerChild</code> connections, the child
|
|
process will die. If <code class="directive">MaxConnectionsPerChild</code> is
|
|
<code>0</code>, then the process will never expire.</p>
|
|
|
|
<p>Setting <code class="directive">MaxConnectionsPerChild</code> to a
|
|
non-zero value limits the amount of memory that a process can consume
|
|
by (accidental) memory leakage.</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="MaxMemFree" id="MaxMemFree">MaxMemFree</a> <a name="maxmemfree" id="maxmemfree">Directive</a> <a title="Permanent link" href="#maxmemfree" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum amount of memory that the main allocator is allowed
|
|
to hold without calling <code>free()</code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxMemFree <var>KBytes</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxMemFree 2048</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code></td></tr>
|
|
</table>
|
|
<p>The <code class="directive">MaxMemFree</code> directive sets the
|
|
maximum number of free Kbytes that every allocator is allowed
|
|
to hold without calling <code>free()</code>. In threaded MPMs, every
|
|
thread has its own allocator. When set
|
|
to zero, the threshold will be set to unlimited.</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="MaxRequestWorkers" id="MaxRequestWorkers">MaxRequestWorkers</a> <a name="maxrequestworkers" id="maxrequestworkers">Directive</a> <a title="Permanent link" href="#maxrequestworkers" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of connections that will be processed
|
|
simultaneously</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxRequestWorkers <var>number</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for details</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code></td></tr>
|
|
</table>
|
|
<p>The <code class="directive">MaxRequestWorkers</code> directive sets the limit
|
|
on the number of simultaneous requests that will be served. Any
|
|
connection attempts over the <code class="directive">MaxRequestWorkers</code>
|
|
limit will normally be queued, up to a number based on the
|
|
<code class="directive"><a href="#listenbacklog">ListenBacklog</a></code>
|
|
directive. Once a child process is freed at the end of a different
|
|
request, the connection will then be serviced.</p>
|
|
|
|
<p>For non-threaded servers (<em>i.e.</em>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>),
|
|
<code class="directive">MaxRequestWorkers</code> translates into the maximum
|
|
number of child processes that will be launched to serve requests.
|
|
The default value is <code>256</code>; to increase it, you must also raise
|
|
<code class="directive"><a href="#serverlimit">ServerLimit</a></code>.</p>
|
|
|
|
<p>For threaded and hybrid servers (<em>e.g.</em> <code class="module"><a href="../mod/event.html">event</a></code>
|
|
or <code class="module"><a href="../mod/worker.html">worker</a></code>), <code class="directive">MaxRequestWorkers</code> restricts
|
|
the total number of threads that will be available to serve clients.
|
|
For hybrid MPMs, the default value is <code>16</code> (<code class="directive"><a href="#serverlimit">ServerLimit</a></code>) multiplied by the value of
|
|
<code>25</code> (<code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code>). Therefore, to increase <code class="directive">MaxRequestWorkers</code> to a value that requires more than 16 processes,
|
|
you must also raise <code class="directive"><a href="#serverlimit">ServerLimit</a></code>.</p>
|
|
|
|
<p><code class="directive">MaxRequestWorkers</code> was called
|
|
<code class="directive">MaxClients</code> before version 2.3.13. The old name is still
|
|
supported.</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="MaxSpareThreads" id="MaxSpareThreads">MaxSpareThreads</a> <a name="maxsparethreads" id="maxsparethreads">Directive</a> <a title="Permanent link" href="#maxsparethreads" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of idle threads</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxSpareThreads <var>number</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for details</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
|
|
</table>
|
|
<p>Maximum number of idle threads. Different MPMs deal with this
|
|
directive differently.</p>
|
|
|
|
<p>For <code class="module"><a href="../mod/worker.html">worker</a></code> and <code class="module"><a href="../mod/event.html">event</a></code>, the default is
|
|
<code>MaxSpareThreads 250</code>. These MPMs deal with idle threads
|
|
on a server-wide basis. If there are too many idle threads in the
|
|
server, then child processes are killed until the number of idle
|
|
threads is less than this number. Additional processes/threads
|
|
might be created if <code class="directive"><a href="#listencoresbucketsratio">ListenCoresBucketsRatio</a></code>
|
|
is enabled.</p>
|
|
|
|
<p>For <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code> the default is
|
|
<code>MaxSpareThreads 100</code>. Since this MPM runs a
|
|
single-process, the spare thread count is also server-wide.</p>
|
|
|
|
<p><code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code> works
|
|
similar to <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>. For
|
|
<code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code> the default value is <code>10</code>.</p>
|
|
|
|
<div class="note"><h3>Restrictions</h3>
|
|
<p>The range of the <code class="directive">MaxSpareThreads</code> value
|
|
is restricted. Apache httpd will correct the given value automatically
|
|
according to the following rules:</p>
|
|
<ul>
|
|
<li><code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code> wants the value to be greater than
|
|
<code class="directive"><a href="#minsparethreads">MinSpareThreads</a></code>.</li>
|
|
|
|
<li>For <code class="module"><a href="../mod/worker.html">worker</a></code> and <code class="module"><a href="../mod/event.html">event</a></code>, the value
|
|
must be greater or equal to the sum of <code class="directive"><a href="#minsparethreads">
|
|
MinSpareThreads</a></code> and <code class="directive"><a href="#threadsperchild">
|
|
ThreadsPerChild</a></code>.</li>
|
|
</ul>
|
|
</div>
|
|
|
|
<h3>See also</h3>
|
|
<ul>
|
|
<li><code class="directive"><a href="#minsparethreads">MinSpareThreads</a></code></li>
|
|
<li><code class="directive"><a href="#startservers">StartServers</a></code></li>
|
|
<li><code class="directive"><a href="../mod/prefork.html#maxspareservers">MaxSpareServers</a></code></li>
|
|
</ul>
|
|
</div>
|
|
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
|
<div class="directive-section"><h2><a name="MinSpareThreads" id="MinSpareThreads">MinSpareThreads</a> <a name="minsparethreads" id="minsparethreads">Directive</a> <a title="Permanent link" href="#minsparethreads" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Minimum number of idle threads available to handle request
|
|
spikes</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MinSpareThreads <var>number</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for details</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
|
|
</table>
|
|
<p>Minimum number of idle threads to handle request spikes.
|
|
Different MPMs deal with this directive differently.</p>
|
|
|
|
<p><code class="module"><a href="../mod/worker.html">worker</a></code> and <code class="module"><a href="../mod/event.html">event</a></code> use a default of
|
|
<code>MinSpareThreads 75</code> and deal with idle threads on a server-wide
|
|
basis. If there aren't enough idle threads in the server, then child
|
|
processes are created until the number of idle threads is greater
|
|
than <var>number</var>. Additional processes/threads
|
|
might be created if <code class="directive"><a href="#listencoresbucketsratio">ListenCoresBucketsRatio</a></code>
|
|
is enabled.</p>
|
|
|
|
<p><code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code> uses a default of
|
|
<code>MinSpareThreads 10</code> and, since it is a single-process
|
|
MPM, tracks this on a server-wide basis.</p>
|
|
|
|
<p><code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code> works
|
|
similar to <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>. For
|
|
<code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code> the default value is <code>5</code>.</p>
|
|
|
|
<h3>See also</h3>
|
|
<ul>
|
|
<li><code class="directive"><a href="#maxsparethreads">MaxSpareThreads</a></code></li>
|
|
<li><code class="directive"><a href="#startservers">StartServers</a></code></li>
|
|
<li><code class="directive"><a href="../mod/prefork.html#minspareservers">MinSpareServers</a></code></li>
|
|
</ul>
|
|
</div>
|
|
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
|
<div class="directive-section"><h2><a name="PidFile" id="PidFile">PidFile</a> <a name="pidfile" id="pidfile">Directive</a> <a title="Permanent link" href="#pidfile" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>File where the server records the process ID
|
|
of the daemon</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PidFile <var>filename</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>PidFile httpd.pid</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
|
|
</table>
|
|
<p>The <code class="directive">PidFile</code> directive sets the file to
|
|
which the server records the process id of the daemon. If the
|
|
filename is not absolute, then it is assumed to be relative to the
|
|
<code class="directive"><a href="../mod/core.html#defaultruntimedir">DefaultRuntimeDir</a></code>.</p>
|
|
|
|
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">PidFile /var/run/apache.pid</pre>
|
|
</div>
|
|
|
|
<p>It is often useful to be able to send the server a signal,
|
|
so that it closes and then re-opens its <code class="directive"><a href="../mod/core.html#errorlog">ErrorLog</a></code> and <code class="directive"><a href="../mod/mod_log_config.html#transferlog">TransferLog</a></code>, and
|
|
re-reads its configuration files. This is done by sending a
|
|
SIGHUP (kill -1) signal to the process id listed in the
|
|
<code class="directive">PidFile</code>.</p>
|
|
|
|
<p>The <code class="directive">PidFile</code> is subject to the same
|
|
warnings about log file placement and <a href="../misc/security_tips.html#serverroot">security</a>.</p>
|
|
|
|
<div class="note"><h3>Note</h3>
|
|
<p>As of Apache HTTP Server 2, we recommended that you only use the <code class="program"><a href="../programs/apachectl.html">apachectl</a></code> script, or the init script that your OS provides,
|
|
for (re-)starting or stopping the server.</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="ReceiveBufferSize" id="ReceiveBufferSize">ReceiveBufferSize</a> <a name="receivebuffersize" id="receivebuffersize">Directive</a> <a title="Permanent link" href="#receivebuffersize" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>TCP receive buffer size</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ReceiveBufferSize <var>bytes</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ReceiveBufferSize 0</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
|
|
</table>
|
|
<p>The server will set the TCP receive buffer size to the number of
|
|
bytes specified.</p>
|
|
|
|
<p>If set to the value of <code>0</code>, the server will use the
|
|
OS default.</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="ScoreBoardFile" id="ScoreBoardFile">ScoreBoardFile</a> <a name="scoreboardfile" id="scoreboardfile">Directive</a> <a title="Permanent link" href="#scoreboardfile" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Location of the file used to store coordination data for
|
|
the child processes</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ScoreBoardFile <var>file-path</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ScoreBoardFile apache_runtime_status</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code></td></tr>
|
|
</table>
|
|
<p>Apache HTTP Server uses a scoreboard to communicate between its parent
|
|
and child processes. Some architectures require a file to facilitate
|
|
this communication. If the file is left unspecified, Apache httpd first
|
|
attempts to create the scoreboard entirely in memory (using anonymous
|
|
shared memory) and, failing that, will attempt to create the file on
|
|
disk (using file-based shared memory). Specifying this directive causes
|
|
Apache httpd to always create the file on the disk.</p>
|
|
|
|
<p>If <var>file-path</var> is not an absolute path, the location specified
|
|
will be relative to the value of
|
|
<code class="directive"><a href="../mod/core.html#defaultruntimedir">DefaultRuntimeDir</a></code>.</p>
|
|
|
|
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">ScoreBoardFile /var/run/apache_runtime_status</pre>
|
|
</div>
|
|
|
|
<p>File-based shared memory is useful for third-party applications
|
|
that require direct access to the scoreboard.</p>
|
|
|
|
<p>If you use a <code class="directive">ScoreBoardFile</code>, then
|
|
you may see improved speed by placing it on a RAM disk. But be
|
|
careful that you heed the same warnings about log file placement
|
|
and <a href="../misc/security_tips.html">security</a>.</p>
|
|
|
|
<h3>See also</h3>
|
|
<ul>
|
|
<li><a href="../stopping.html">Stopping and Restarting
|
|
Apache HTTP Server</a></li>
|
|
</ul>
|
|
</div>
|
|
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
|
<div class="directive-section"><h2><a name="SendBufferSize" id="SendBufferSize">SendBufferSize</a> <a name="sendbuffersize" id="sendbuffersize">Directive</a> <a title="Permanent link" href="#sendbuffersize" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>TCP buffer size</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SendBufferSize <var>bytes</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SendBufferSize 0</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
|
|
</table>
|
|
<p>Sets the server's TCP send buffer size to the number of bytes
|
|
specified. It is often useful to set this past the OS's standard
|
|
default value on high speed, high latency connections
|
|
(<em>i.e.</em>, 100ms or so, such as transcontinental fast pipes).</p>
|
|
|
|
<p>If set to the value of <code>0</code>, the server will use the
|
|
default value provided by your OS.</p>
|
|
|
|
<p>Further configuration of your operating system may be required to elicit
|
|
better performance on high speed, high latency connections.</p>
|
|
|
|
<div class="note"> <p> On some operating systems, changes in TCP behavior resulting
|
|
from a larger <code class="directive">SendBufferSize</code> may not be seen unless
|
|
<code class="directive"><a href="../mod/core.html#enablesendfile">EnableSendfile</a></code> is set to OFF. This
|
|
interaction applies only to static files.</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="ServerLimit" id="ServerLimit">ServerLimit</a> <a name="serverlimit" id="serverlimit">Directive</a> <a title="Permanent link" href="#serverlimit" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Upper limit on configurable number of processes</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerLimit <var>number</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for details</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code></td></tr>
|
|
</table>
|
|
<p>For the <code class="module"><a href="../mod/prefork.html">prefork</a></code> MPM, this directive sets the
|
|
maximum configured value for <code class="directive"><a href="#maxrequestworkers">MaxRequestWorkers</a></code> for the lifetime of the
|
|
Apache httpd process. For the <code class="module"><a href="../mod/worker.html">worker</a></code> and <code class="module"><a href="../mod/event.html">event
|
|
</a></code> MPMs, this directive in combination with <code class="directive"><a href="#threadlimit">ThreadLimit</a></code> sets
|
|
the maximum configured value for <code class="directive"><a href="#maxrequestworkers">MaxRequestWorkers</a></code> for the lifetime of the
|
|
Apache httpd process. For the <code class="module"><a href="../mod/event.html">event</a></code> MPM, this directive
|
|
also defines how many old server processes may keep running and finish processing
|
|
open connections.
|
|
Any attempts to change this directive during a restart will be ignored, but
|
|
<code class="directive"><a href="#maxrequestworkers">MaxRequestWorkers</a></code> can be modified
|
|
during a restart.</p>
|
|
|
|
<p>Special care must be taken when using this directive. If
|
|
<code class="directive">ServerLimit</code> is set to a value much higher
|
|
than necessary, extra, unused shared memory will be allocated. If
|
|
both <code class="directive">ServerLimit</code> and <code class="directive"><a href="#maxrequestworkers">MaxRequestWorkers</a></code> are set to values
|
|
higher than the system can handle, Apache httpd may not start or the
|
|
system may become unstable.</p>
|
|
|
|
<p>With the <code class="module"><a href="../mod/prefork.html">prefork</a></code> MPM, use this directive only
|
|
if you need to set <code class="directive"><a href="#maxrequestworkers">MaxRequestWorkers</a></code> higher than 256 (default).
|
|
Do not set the value of this directive any higher than what you
|
|
might want to set <code class="directive"><a href="#maxrequestworkers">MaxRequestWorkers</a></code> to.</p>
|
|
|
|
<p>With <code class="module"><a href="../mod/worker.html">worker</a></code>, use this directive only if your
|
|
<code class="directive"><a href="#maxrequestworkers">MaxRequestWorkers
|
|
</a></code> and <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code>
|
|
settings require more than 16 server processes (default). Do not set
|
|
the value of this directive any higher than the number of server
|
|
processes required by what you may want for <code class="directive"><a href="#maxrequestworkers">MaxRequestWorkers </a></code> and <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code>.</p>
|
|
|
|
<p>With <code class="module"><a href="../mod/event.html">event</a></code>, increase this directive if the process
|
|
number defined by your <code class="directive"><a href="#maxrequestworkers">MaxRequestWorkers</a></code> and <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code> settings, plus the
|
|
number of gracefully shutting down processes, is more than 16 server
|
|
processes (default).</p>
|
|
|
|
<div class="note"><h3>Note</h3>
|
|
<p>There is a hard limit of <code>ServerLimit 20000</code> compiled
|
|
into the server (for the <code class="module"><a href="../mod/prefork.html">prefork</a></code> MPM 200000). This is
|
|
intended to avoid nasty effects caused by typos. To increase it
|
|
even further past this limit, you will need to modify the value of
|
|
MAX_SERVER_LIMIT in the mpm source file and rebuild the server.</p>
|
|
</div>
|
|
|
|
<h3>See also</h3>
|
|
<ul>
|
|
<li><a href="../stopping.html">Stopping and Restarting Apache HTTP Server</a></li>
|
|
</ul>
|
|
</div>
|
|
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
|
<div class="directive-section"><h2><a name="StartServers" id="StartServers">StartServers</a> <a name="startservers" id="startservers">Directive</a> <a title="Permanent link" href="#startservers" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of child server processes created at startup</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>StartServers <var>number</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for details</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
|
|
</table>
|
|
<p>The <code class="directive">StartServers</code> directive sets the
|
|
number of child server processes created on startup. As the number
|
|
of processes is dynamically controlled depending on the load, (see
|
|
<code class="directive"><a href="#minsparethreads">MinSpareThreads</a></code>,
|
|
<code class="directive"><a href="#maxsparethreads">MaxSpareThreads</a></code>,
|
|
<code class="directive"><a href="../mod/prefork.html#minspareservers">MinSpareServers</a></code>, <code class="directive"><a href="../mod/prefork.html#maxspareservers">MaxSpareServers</a></code>)
|
|
there is usually little reason to adjust this parameter.</p>
|
|
|
|
<p>The default value differs from MPM to MPM. <code class="module"><a href="../mod/worker.html">worker</a></code> and
|
|
<code class="module"><a href="../mod/event.html">event</a></code> default to <code>StartServers 3</code>; <code class="module"><a href="../mod/prefork.html">
|
|
prefork</a></code> defaults to <code>5</code>; <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code>
|
|
defaults to <code>2</code>.</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="StartThreads" id="StartThreads">StartThreads</a> <a name="startthreads" id="startthreads">Directive</a> <a title="Permanent link" href="#startthreads" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of threads created on startup</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>StartThreads <var>number</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for details</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><code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code></td></tr>
|
|
</table>
|
|
<p>Number of threads created on startup. As the
|
|
number of threads is dynamically controlled depending on the
|
|
load, (see
|
|
<code class="directive"><a href="#minsparethreads">MinSpareThreads</a></code>,
|
|
<code class="directive"><a href="#maxsparethreads">MaxSpareThreads</a></code>,
|
|
<code class="directive"><a href="../mod/prefork.html#minspareservers">MinSpareServers</a></code>, <code class="directive"><a href="../mod/prefork.html#maxspareservers">MaxSpareServers</a></code>)
|
|
there is usually little reason to adjust this
|
|
parameter.</p>
|
|
|
|
<p>For <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code> the default is
|
|
<code>StartThreads 50</code> and, since there is only a single
|
|
process, this is the total number of threads created at startup to
|
|
serve requests.</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="ThreadLimit" id="ThreadLimit">ThreadLimit</a> <a name="threadlimit" id="threadlimit">Directive</a> <a title="Permanent link" href="#threadlimit" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the upper limit on the configurable number of threads
|
|
per child process</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ThreadLimit <var>number</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for details</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code></td></tr>
|
|
</table>
|
|
<p>This directive sets the maximum configured value for <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code> for the lifetime
|
|
of the Apache httpd process. Any attempts to change this directive
|
|
during a restart will be ignored, but <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code> can be modified
|
|
during a restart up to the value of this directive.</p>
|
|
|
|
<p>Special care must be taken when using this directive. If
|
|
<code class="directive">ThreadLimit</code> is set to a value much higher
|
|
than <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code>,
|
|
extra unused shared memory will be allocated. If both
|
|
<code class="directive">ThreadLimit</code> and <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code> are set to values
|
|
higher than the system can handle, Apache httpd may not start or the
|
|
system may become unstable. Do not set the value of this directive
|
|
any higher than your greatest predicted setting of <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code> for the
|
|
current run of Apache httpd.</p>
|
|
|
|
<p>The default value for <code class="directive">ThreadLimit</code> is
|
|
<code>1920</code> when used with <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code> and
|
|
<code>64</code> when used with the others.</p>
|
|
|
|
<div class="note"><h3>Note</h3>
|
|
<p>There is a hard limit of <code>ThreadLimit 20000</code> (or
|
|
<code>ThreadLimit 100000</code> with <code class="module"><a href="../mod/event.html">event</a></code>,
|
|
<code>ThreadLimit 15000</code> with <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>)
|
|
compiled into the server. This is intended to avoid nasty effects
|
|
caused by typos. To increase it even further past this limit, you
|
|
will need to modify the value of MAX_THREAD_LIMIT in the mpm
|
|
source file and rebuild the server.</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="ThreadsPerChild" id="ThreadsPerChild">ThreadsPerChild</a> <a name="threadsperchild" id="threadsperchild">Directive</a> <a title="Permanent link" href="#threadsperchild" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of threads created by each child process</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ThreadsPerChild <var>number</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for details</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code></td></tr>
|
|
</table>
|
|
<p>This directive sets the number of threads created by each
|
|
child process. The child creates these threads at startup and
|
|
never creates more. If using an MPM like <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>,
|
|
where there is only one child process, this number should be high
|
|
enough to handle the entire load of the server. If using an MPM
|
|
like <code class="module"><a href="../mod/worker.html">worker</a></code>, where there are multiple child processes,
|
|
the <em>total</em> number of threads should be high enough to handle
|
|
the common load on the server.</p>
|
|
|
|
<p>The default value for <code class="directive">ThreadsPerChild</code> is
|
|
<code>64</code> when used with <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code> and
|
|
<code>25</code> when used with the others.</p>
|
|
|
|
<p>The value of <code class="directive">ThreadsPerChild</code> can not exceed the
|
|
value of <code class="directive"><a href="#threadlimit">ThreadLimit</a></code>. If a
|
|
higher value is configured, it will be automatically reduced at start-up
|
|
and a warning will be logged. The relationship between these 2 directives
|
|
is explained in <code class="directive"><a href="#threadlimit">ThreadLimit</a></code>.</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="ThreadStackSize" id="ThreadStackSize">ThreadStackSize</a> <a name="threadstacksize" id="threadstacksize">Directive</a> <a title="Permanent link" href="#threadstacksize" class="permalink">¶</a></h2>
|
|
<table class="directive">
|
|
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The size in bytes of the stack used by threads handling
|
|
client connections</td></tr>
|
|
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ThreadStackSize <var>size</var></code></td></tr>
|
|
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>65536 on NetWare; varies on other operating systems</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><code class="module"><a href="../mod/event.html">event</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
|
|
</table>
|
|
<p>The <code class="directive">ThreadStackSize</code> directive sets the
|
|
size of the stack (for autodata) of threads which handle client
|
|
connections and call modules to help process those connections.
|
|
In most cases the operating system default for stack size is
|
|
reasonable, but there are some conditions where it may need to be
|
|
adjusted:</p>
|
|
|
|
<ul>
|
|
<li>On platforms with a relatively small default thread stack size
|
|
(e.g., HP-UX), Apache httpd may crash when using some third-party modules
|
|
which use a relatively large amount of autodata storage. Those
|
|
same modules may have worked fine on other platforms where the
|
|
default thread stack size is larger. This type of crash is
|
|
resolved by setting <code class="directive">ThreadStackSize</code> to a
|
|
value higher than the operating system default. This type of
|
|
adjustment is necessary only if the provider of the third-party
|
|
module specifies that it is required, or if diagnosis of an Apache httpd
|
|
crash indicates that the thread stack size was too small.</li>
|
|
|
|
<li>On platforms where the default thread stack size is
|
|
significantly larger than necessary for the web server
|
|
configuration, a higher number of threads per child process
|
|
will be achievable if <code class="directive">ThreadStackSize</code> is
|
|
set to a value lower than the operating system default. This type
|
|
of adjustment should only be made in a test environment which allows
|
|
the full set of web server processing to be exercised, as there
|
|
may be infrequent requests which require more stack to process.
|
|
The minimum required stack size strongly depends on the modules
|
|
used, but any change in the web server configuration can invalidate
|
|
the current <code class="directive">ThreadStackSize</code> setting.</li>
|
|
|
|
<li>On Linux, this directive can only be used to increase the default
|
|
stack size, as the underlying system call uses the value as a
|
|
<em>minimum</em> stack size. The (often large) soft limit for
|
|
<code>ulimit -s</code> (8MB if unlimited) is used as the default stack
|
|
size.</li>
|
|
</ul>
|
|
|
|
<div class="note">It is recommended to not reduce <code class="directive">ThreadStackSize</code>
|
|
unless a high number of threads per child process is needed. On some
|
|
platforms (including Linux), a setting of 128000 is already too low and
|
|
causes crashes with some common modules.</div>
|
|
|
|
</div>
|
|
</div>
|
|
<div class="bottomlang">
|
|
<p><span>Available Languages: </span><a href="../de/mod/mpm_common.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
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|
<a href="../en/mod/mpm_common.html" title="English"> en </a> |
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|
<a href="../fr/mod/mpm_common.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
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<a href="../ja/mod/mpm_common.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
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<a href="../tr/mod/mpm_common.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
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</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div>
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