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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-07 02:04:06 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-07 02:04:06 +0000
commit5dff2d61cc1c27747ee398e04d8e02843aabb1f8 (patch)
treea67c336b406c8227bac912beb74a1ad3cdc55100 /docs/manual/stopping.html.en
parentInitial commit. (diff)
downloadapache2-upstream.tar.xz
apache2-upstream.zip
Adding upstream version 2.4.38.upstream/2.4.38upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+<?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>
+<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>Stopping and Restarting Apache HTTP Server - Apache HTTP Server Version 2.4</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 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 id="manual-page"><div id="page-header">
+<p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/directives.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 2.4</p>
+<img alt="" src="./images/feather.png" /></div>
+<div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="./images/left.gif" /></a></div>
+<div id="path">
+<a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="./">Version 2.4</a></div><div id="page-content"><div id="preamble"><h1>Stopping and Restarting Apache HTTP Server</h1>
+<div class="toplang">
+<p><span>Available Languages: </span><a href="./de/stopping.html" hreflang="de" rel="alternate" title="Deutsch">&nbsp;de&nbsp;</a> |
+<a href="./en/stopping.html" title="English">&nbsp;en&nbsp;</a> |
+<a href="./es/stopping.html" hreflang="es" rel="alternate" title="Español">&nbsp;es&nbsp;</a> |
+<a href="./fr/stopping.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a> |
+<a href="./ja/stopping.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a> |
+<a href="./ko/stopping.html" hreflang="ko" rel="alternate" title="Korean">&nbsp;ko&nbsp;</a> |
+<a href="./tr/stopping.html" hreflang="tr" rel="alternate" title="Türkçe">&nbsp;tr&nbsp;</a></p>
+</div>
+
+ <p>This document covers stopping and restarting Apache HTTP Server on
+ Unix-like systems. Windows NT, 2000 and XP users should see
+ <a href="platform/windows.html#winsvc">Running httpd as a
+ Service</a> and Windows 9x and ME users should see <a href="platform/windows.html#wincons">Running httpd as a
+ Console Application</a> for information on how to control
+ httpd on those platforms.</p>
+</div>
+<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#introduction">Introduction</a></li>
+<li><img alt="" src="./images/down.gif" /> <a href="#term">Stop Now</a></li>
+<li><img alt="" src="./images/down.gif" /> <a href="#graceful">Graceful Restart</a></li>
+<li><img alt="" src="./images/down.gif" /> <a href="#hup">Restart Now</a></li>
+<li><img alt="" src="./images/down.gif" /> <a href="#gracefulstop">Graceful Stop</a></li>
+</ul><h3>See also</h3><ul class="seealso"><li><code class="program"><a href="./programs/httpd.html">httpd</a></code></li><li><code class="program"><a href="./programs/apachectl.html">apachectl</a></code></li><li><a href="invoking.html">Starting</a></li><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="introduction" id="introduction">Introduction</a></h2>
+
+ <p>In order to stop or restart the Apache HTTP Server, you must send a signal to
+ the running <code class="program"><a href="./programs/httpd.html">httpd</a></code> processes. There are two ways to
+ send the signals. First, you can use the unix <code>kill</code>
+ command to directly send signals to the processes. You will
+ notice many <code class="program"><a href="./programs/httpd.html">httpd</a></code> executables running on your system,
+ but you should not send signals to any of them except the parent,
+ whose pid is in the <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code>. That is to say you
+ shouldn't ever need to send signals to any process except the
+ parent. There are four signals that you can send the parent:
+ <code><a href="#term">TERM</a></code>,
+ <code><a href="#graceful">USR1</a></code>,
+ <code><a href="#hup">HUP</a></code>, and
+ <code><a href="#gracefulstop">WINCH</a></code>, which
+ will be described in a moment.</p>
+
+ <p>To send a signal to the parent you should issue a command
+ such as:</p>
+
+<div class="example"><p><code>kill -TERM `cat /usr/local/apache2/logs/httpd.pid`</code></p></div>
+
+ <p>The second method of signaling the <code class="program"><a href="./programs/httpd.html">httpd</a></code> processes
+ is to use the <code>-k</code> command line options: <code>stop</code>,
+ <code>restart</code>, <code>graceful</code> and <code>graceful-stop</code>,
+ as described below. These are arguments to the <code class="program"><a href="./programs/httpd.html">httpd</a></code> binary, but we recommend that
+ you send them using the <code class="program"><a href="./programs/apachectl.html">apachectl</a></code> control script, which
+ will pass them through to <code class="program"><a href="./programs/httpd.html">httpd</a></code>.</p>
+
+ <p>After you have signaled <code class="program"><a href="./programs/httpd.html">httpd</a></code>, you can read about
+ its progress by issuing:</p>
+
+<div class="example"><p><code>tail -f /usr/local/apache2/logs/error_log</code></p></div>
+
+ <p>Modify those examples to match your <code class="directive"><a href="./mod/core.html#serverroot">ServerRoot</a></code> and <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code> settings.</p>
+</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="term" id="term">Stop Now</a></h2>
+
+<dl><dt>Signal: TERM</dt>
+<dd><code>apachectl -k stop</code></dd>
+</dl>
+
+ <p>Sending the <code>TERM</code> or <code>stop</code> signal to
+ the parent causes it to immediately attempt to kill off all of its
+ children. It may take it several seconds to complete killing off
+ its children. Then the parent itself exits. Any requests in
+ progress are terminated, and no further requests are served.</p>
+</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="graceful" id="graceful">Graceful Restart</a></h2>
+
+<dl><dt>Signal: USR1</dt>
+<dd><code>apachectl -k graceful</code></dd>
+</dl>
+
+ <p>The <code>USR1</code> or <code>graceful</code> signal causes
+ the parent process to <em>advise</em> the children to exit after
+ their current request (or to exit immediately if they're not
+ serving anything). The parent re-reads its configuration files and
+ re-opens its log files. As each child dies off the parent replaces
+ it with a child from the new <em>generation</em> of the
+ configuration, which begins serving new requests immediately.</p>
+
+ <p>This code is designed to always respect the process control
+ directive of the MPMs, so the number of processes and threads
+ available to serve clients will be maintained at the appropriate
+ values throughout the restart process. Furthermore, it respects
+ <code class="directive"><a href="./mod/mpm_common.html#startservers">StartServers</a></code> in the
+ following manner: if after one second at least <code class="directive"><a href="./mod/mpm_common.html#startservers">StartServers</a></code> new children have not
+ been created, then create enough to pick up the slack. Hence the
+ code tries to maintain both the number of children appropriate for
+ the current load on the server, and respect your wishes with the
+ <code class="directive"><a href="./mod/mpm_common.html#startservers">StartServers</a></code>
+ parameter.</p>
+
+ <p>Users of <code class="module"><a href="./mod/mod_status.html">mod_status</a></code>
+ will notice that the server statistics are <strong>not</strong>
+ set to zero when a <code>USR1</code> is sent. The code was
+ written to both minimize the time in which the server is unable
+ to serve new requests (they will be queued up by the operating
+ system, so they're not lost in any event) and to respect your
+ tuning parameters. In order to do this it has to keep the
+ <em>scoreboard</em> used to keep track of all children across
+ generations.</p>
+
+ <p>The status module will also use a <code>G</code> to indicate
+ those children which are still serving requests started before
+ the graceful restart was given.</p>
+
+ <p>At present there is no way for a log rotation script using
+ <code>USR1</code> to know for certain that all children writing
+ the pre-restart log have finished. We suggest that you use a
+ suitable delay after sending the <code>USR1</code> signal
+ before you do anything with the old log. For example if most of
+ your hits take less than 10 minutes to complete for users on
+ low bandwidth links then you could wait 15 minutes before doing
+ anything with the old log.</p>
+
+ <div class="note">
+ <p>When you issue a restart, a syntax check is first run, to
+ ensure that there are no errors in the configuration files.
+ If your configuration file has errors in it, you will get an
+ error message about that syntax error, and the server will refuse to
+ restart. This avoids the situation where the server halts and then
+ cannot restart, leaving you with a non-functioning server.</p>
+
+ <p>This still will not
+ guarantee that the server will restart correctly. To check the
+ semantics of the configuration files as well as the syntax, you
+ can try starting <code class="program"><a href="./programs/httpd.html">httpd</a></code> as a non-root user. If there
+ are no errors it will attempt to open its sockets and logs and fail
+ because it's not root (or because the currently running
+ <code class="program"><a href="./programs/httpd.html">httpd</a></code> already has those ports bound). If it fails
+ for any other reason then it's probably a config file error and the error
+ should be fixed before issuing the graceful restart.</p></div>
+</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="hup" id="hup">Restart Now</a></h2>
+
+<dl><dt>Signal: HUP</dt>
+<dd><code>apachectl -k restart</code></dd>
+</dl>
+
+ <p>Sending the <code>HUP</code> or <code>restart</code> signal to
+ the parent causes it to kill off its children like in
+ <code>TERM</code>, but the parent doesn't exit. It re-reads its
+ configuration files, and re-opens any log files. Then it spawns a
+ new set of children and continues serving hits.</p>
+
+ <p>Users of <code class="module"><a href="./mod/mod_status.html">mod_status</a></code>
+ will notice that the server statistics are set to zero when a
+ <code>HUP</code> is sent.</p>
+
+<div class="note">As with a graceful restart, a syntax check is run before the
+restart is attempted. If your configuration file has errors in it, the
+restart will not be attempted, and you will receive notification of the
+syntax error(s).</div>
+</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="gracefulstop" id="gracefulstop">Graceful Stop</a></h2>
+
+<dl><dt>Signal: WINCH</dt>
+<dd><code>apachectl -k graceful-stop</code></dd>
+</dl>
+
+ <p>The <code>WINCH</code> or <code>graceful-stop</code> signal causes
+ the parent process to <em>advise</em> the children to exit after
+ their current request (or to exit immediately if they're not
+ serving anything). The parent will then remove its <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code> and cease listening on
+ all ports. The parent will continue to run, and monitor children
+ which are handling requests. Once all children have finalised
+ and exited or the timeout specified by the <code class="directive"><a href="./mod/mpm_common.html#gracefulshutdowntimeout">GracefulShutdownTimeout</a></code> has been
+ reached, the parent will also exit. If the timeout is reached,
+ any remaining children will be sent the <code>TERM</code> signal
+ to force them to exit.</p>
+
+ <p>A <code>TERM</code> signal will immediately terminate the
+ parent process and all children when in the "graceful" state. However
+ as the <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code> will
+ have been removed, you will not be able to use
+ <code>apachectl</code> or <code>httpd</code> to send this signal.</p>
+
+ <div class="note"><p>The <code>graceful-stop</code> signal allows you to run multiple
+ identically configured instances of <code class="program"><a href="./programs/httpd.html">httpd</a></code> at the
+ same time. This is a powerful feature when performing graceful
+ upgrades of httpd, however it can also cause deadlocks and race
+ conditions with some configurations.</p>
+
+ <p>Care has been taken to ensure that on-disk files such as lock files
+ (<code class="directive"><a href="./mod/core.html#mutex">Mutex</a></code>) and Unix socket files
+ (<code class="directive"><a href="./mod/mod_cgid.html#scriptsock">ScriptSock</a></code>) contain the server
+ PID, and should coexist without problem. However, if a configuration
+ directive, third-party module or persistent CGI utilises any other on-disk
+ lock or state files, care should be taken to ensure that multiple running
+ instances of <code class="program"><a href="./programs/httpd.html">httpd</a></code> do not clobber each other's files.</p>
+
+ <p>You should also be wary of other potential race conditions, such as
+ using <code class="program"><a href="./programs/rotatelogs.html">rotatelogs</a></code> style piped logging. Multiple running
+ instances of <code class="program"><a href="./programs/rotatelogs.html">rotatelogs</a></code> attempting to rotate the same
+ logfiles at the same time may destroy each other's logfiles.</p></div>
+</div></div>
+<div class="bottomlang">
+<p><span>Available Languages: </span><a href="./de/stopping.html" hreflang="de" rel="alternate" title="Deutsch">&nbsp;de&nbsp;</a> |
+<a href="./en/stopping.html" title="English">&nbsp;en&nbsp;</a> |
+<a href="./es/stopping.html" hreflang="es" rel="alternate" title="Español">&nbsp;es&nbsp;</a> |
+<a href="./fr/stopping.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a> |
+<a href="./ja/stopping.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a> |
+<a href="./ko/stopping.html" hreflang="ko" rel="alternate" title="Korean">&nbsp;ko&nbsp;</a> |
+<a href="./tr/stopping.html" hreflang="tr" rel="alternate" title="Türkçe">&nbsp;tr&nbsp;</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&amp;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>
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