<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
+<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head>
+<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type" />
+<!--
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
This file is generated from xml source: DO NOT EDIT
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
-->
-<title>prefork - Apache HTTP Server</title>
+<title>prefork - Apache HTTP Server Version 2.5</title>
<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
-<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" />
+<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" />
+<script src="../style/scripts/prettify.min.js" type="text/javascript">
+</script>
+
<link href="../images/favicon.ico" rel="shortcut icon" /></head>
<body>
<div id="page-header">
-<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>
-<p class="apache">Apache HTTP Server Version 2.1</p>
-<img alt="" src="../images/feather.gif" /></div>
+<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>
+<p class="apache">Apache HTTP Server Version 2.5</p>
+<img alt="" src="../images/feather.png" /></div>
<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
<div id="path">
-<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs
-project/">Documentation</a> > <a href="../">Version 2.1</a> > <a href="./">Modules</a></div>
+<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>
<div id="page-content">
<div id="preamble"><h1>Apache MPM prefork</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="../de/mod/prefork.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
<a href="../en/mod/prefork.html" title="English"> en </a> |
-<a href="../ja/mod/prefork.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
+<a href="../fr/mod/prefork.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
+<a href="../ja/mod/prefork.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
+<a href="../tr/mod/prefork.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
</div>
<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Implements a non-threaded, pre-forking web server</td></tr>
<tr><th><a href="module-dict.html#Status">Status:</a></th><td>MPM</td></tr>
<h3>Summary</h3>
<p>This Multi-Processing Module (MPM) implements a non-threaded,
- pre-forking web server that handles requests in a manner similar
- to Apache 1.3. It is appropriate for sites that need to avoid
+ pre-forking web server. Each server process may answer incoming
+ requests, and a parent process manages the size of the server pool.
+ It is appropriate for sites that need to avoid
threading for compatibility with non-thread-safe libraries. It
is also the best MPM for isolating each request, so that a problem
with a single request will not affect any other.</p>
<p>This MPM is very self-regulating, so it is rarely necessary to
adjust its configuration directives. Most important is that
- <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code> be big enough to
- handle as many simultaneous requests as you expect to receive, but
+ <code class="directive"><a href="../mod/mpm_common.html#maxrequestworkers">MaxRequestWorkers</a></code> be big enough
+ to handle as many simultaneous requests as you expect to receive, but
small enough to assure that there is enough physical RAM for all
processes.</p>
</div>
-<div id="quickview"><h3 class="directives">Directives</h3>
+<div id="quickview"><h3>Topics</h3>
+<ul id="topics">
+<li><img alt="" src="../images/down.gif" /> <a href="#how-it-works">How it Works</a></li>
+</ul><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="mod_unixd.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#maxconnectionsperchild">MaxConnectionsPerChild</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#maxrequestworkers">MaxRequestWorkers</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#maxspareservers">MaxSpareServers</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#minspareservers">MinSpareServers</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#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#user">User</a></li>
+<li><img alt="" src="../images/right.gif" /> <a href="mod_unixd.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>
-</ul><h3>See also</h3>
+<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_prefork">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=mpm_prefork">Report a bug</a></li></ul><h3>See also</h3>
<ul class="seealso">
-<li><a href="../bind.html">Setting which addresses and ports Apache
+<li><a href="../bind.html">Setting which addresses and ports Apache HTTP Server
uses</a></li>
-</ul></div>
+<li><a href="#comments_section">Comments</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>A single control process is responsible for launching child
processes which listen for connections and serve them when they
- arrive. Apache always tries to maintain several <dfn>spare</dfn>
+ arrive. Apache httpd always tries to maintain several <dfn>spare</dfn>
or idle server processes, which stand ready to serve incoming
requests. In this way, clients do not need to wait for a new
child processes to be forked before their requests can be
<p>The <code class="directive"><a href="../mod/mpm_common.html#startservers">StartServers</a></code>,
<code class="directive"><a href="#minspareservers">MinSpareServers</a></code>,
<code class="directive"><a href="#maxspareservers">MaxSpareServers</a></code>, and
- <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code> regulate how
+ <code class="directive"><a href="../mod/mpm_common.html#maxrequestworkers">MaxRequestWorkers</a></code> regulate how
the parent process creates children to serve requests. In general,
- Apache is very self-regulating, so most sites do not need to
+ Apache httpd is very self-regulating, so most sites do not need to
adjust these directives from their default values. Sites which
need to serve more than 256 simultaneous requests may need to
- increase <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code>,
- while sites with limited memory may need to decrease <code class="directive"><a href="../mod/mpm_common.html#maxclients">MaxClients</a></code> to keep the server from
+ increase <code class="directive"><a href="../mod/mpm_common.html#maxrequestworkers">MaxRequestWorkers</a></code>,
+ while sites with limited memory may need to decrease <code class="directive"><a href="../mod/mpm_common.html#maxrequestworkers">MaxRequestWorkers</a></code> to keep the server from
thrashing (swapping memory to disk and back). More information
about tuning process creation is provided in the <a href="../misc/perf-tuning.html">performance hints</a>
documentation.</p>
<p>While the parent process is usually started as <code>root</code>
under Unix in order to bind to port 80, the child processes are
- launched by Apache as a less-privileged user. The <code class="directive"><a href="../mod/mpm_common.html#user">User</a></code> and <code class="directive"><a href="../mod/mpm_common.html#group">Group</a></code> directives are used to set
- the privileges of the Apache child processes. The child processes
+ launched by Apache httpd as a less-privileged user. The <code class="directive"><a href="../mod/mod_unixd.html#user">User</a></code> and <code class="directive"><a href="../mod/mod_unixd.html#group">Group</a></code> directives are used to set
+ the privileges of the Apache httpd child processes. The child processes
must be able to read all the content that will be served, but
should have as few privileges beyond that as possible.</p>
- <p><code class="directive"><a href="../mod/mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></code>
+ <p><code class="directive"><a href="../mod/mpm_common.html#maxconnectionsperchild">MaxConnectionsPerChild</a></code>
controls how frequently the server recycles processes by killing
old ones and launching new ones.</p>
+
+ <p>This MPM uses the <code>mpm-accept</code> mutex to serialize
+ access to incoming connections when subject to the thundering herd
+ problem (generally, when there are multiple listening sockets).
+ The implementation aspects of this mutex can be configured with the
+ <code class="directive"><a href="../mod/core.html#mutex">Mutex</a></code> directive. The <a href="../misc/perf-tuning.html">performance hints</a>
+ documentation has additional information about this mutex.</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="MaxSpareServers" id="MaxSpareServers">MaxSpareServers</a> <a name="maxspareservers" id="maxspareservers">Directive</a></h2>
<p>Tuning of this parameter should only be necessary on very
busy sites. Setting this parameter to a large number is almost
always a bad idea. If you are trying to set the value equal to or lower than
- <code class="directive"><a href="#minspareservers">MinSpareServers</a></code>, Apache
+ <code class="directive"><a href="#minspareservers">MinSpareServers</a></code>, Apache HTTP Server
will automatically adjust it to <code class="directive">MinSpareServers</code><code> + 1</code>.</p>
<h3>See also</h3>
<ul>
<li><code class="directive"><a href="#minspareservers">MinSpareServers</a></code></li>
<li><code class="directive"><a href="../mod/mpm_common.html#startservers">StartServers</a></code></li>
+<li><code class="directive"><a href="../mod/mpm_common.html#maxsparethreads">MaxSpareThreads</a></code></li>
</ul>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
desired minimum number of <em>idle</em> child server processes. An
idle process is one which is not handling a request. If there are
fewer than <code class="directive">MinSpareServers</code> idle, then the parent
- process creates new children at a maximum rate of 1 per second.</p>
+ process creates new children: It will spawn one, wait a second, then spawn
+ two, wait a second, then spawn four, and it will
+ continue exponentially until it is spawning 32 children per second. It will
+ stop whenever it satisfies the <code class="directive">MinSpareServers</code>
+ setting.</p>
<p>Tuning of this parameter should only be necessary on very
busy sites. Setting this parameter to a large number is almost
<ul>
<li><code class="directive"><a href="#maxspareservers">MaxSpareServers</a></code></li>
<li><code class="directive"><a href="../mod/mpm_common.html#startservers">StartServers</a></code></li>
+<li><code class="directive"><a href="../mod/mpm_common.html#minsparethreads">MinSpareThreads</a></code></li>
</ul>
</div>
</div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="../de/mod/prefork.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
<a href="../en/mod/prefork.html" title="English"> en </a> |
-<a href="../ja/mod/prefork.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
-</div><div id="footer">
-<p class="apache">Copyright 1995-2005 The Apache Software Foundation or its licensors, as applicable.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
-<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>
+<a href="../fr/mod/prefork.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
+<a href="../ja/mod/prefork.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
+<a href="../tr/mod/prefork.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
+</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 again 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 Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
+<script type="text/javascript"><!--//--><![CDATA[//><!--
+var comments_shortname = 'httpd';
+var comments_identifier = 'http://httpd.apache.org/docs/trunk/mod/prefork.html';
+(function(w, d) {
+ if (w.location.hostname.toLowerCase() == "httpd.apache.org") {
+ d.write('<div id="comments_thread"><\/div>');
+ var s = d.createElement('script');
+ s.type = 'text/javascript';
+ s.async = true;
+ s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier;
+ (d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s);
+ }
+ else {
+ d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>');
+ }
+})(window, document);
+//--><!]]></script></div><div id="footer">
+<p class="apache">Copyright 2017 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>
+<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></div><script type="text/javascript"><!--//--><![CDATA[//><!--
+if (typeof(prettyPrint) !== 'undefined') {
+ prettyPrint();
+}
+//--><!]]></script>
</body></html>
\ No newline at end of file
projects / apache / blobdiff