1<?xml version="1.0" encoding="UTF-8"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head> 4<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" /> 5<!-- 6 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 7 This file is generated from xml source: DO NOT EDIT 8 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 9 --> 10<title>Stopping and Restarting Apache HTTP Server - Apache HTTP Server Version 2.4</title> 11<link href="./style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> 12<link href="./style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> 13<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" /> 14<script src="./style/scripts/prettify.min.js" type="text/javascript"> 15</script> 16 17<link href="./images/favicon.ico" rel="shortcut icon" /></head> 18<body id="manual-page"><div id="page-header"> 19<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> 20<p class="apache">Apache HTTP Server Version 2.4</p> 21<img alt="" src="./images/feather.png" /></div> 22<div class="up"><a href="./"><img title="<-" alt="<-" src="./images/left.gif" /></a></div> 23<div id="path"> 24<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 2.4</a></div><div id="page-content"><div id="preamble"><h1>Stopping and Restarting Apache HTTP Server</h1> 25<div class="toplang"> 26<p><span>Available Languages: </span><a href="./de/stopping.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> | 27<a href="./en/stopping.html" title="English"> en </a> | 28<a href="./es/stopping.html" hreflang="es" rel="alternate" title="Español"> es </a> | 29<a href="./fr/stopping.html" hreflang="fr" rel="alternate" title="Français"> fr </a> | 30<a href="./ja/stopping.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 31<a href="./ko/stopping.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | 32<a href="./tr/stopping.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p> 33</div> 34 35 <p>This document covers stopping and restarting Apache HTTP Server on 36 Unix-like systems. Windows NT, 2000 and XP users should see 37 <a href="platform/windows.html#winsvc">Running httpd as a 38 Service</a> and Windows 9x and ME users should see <a href="platform/windows.html#wincons">Running httpd as a 39 Console Application</a> for information on how to control 40 httpd on those platforms.</p> 41</div> 42<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> 43<li><img alt="" src="./images/down.gif" /> <a href="#term">Stop Now</a></li> 44<li><img alt="" src="./images/down.gif" /> <a href="#graceful">Graceful Restart</a></li> 45<li><img alt="" src="./images/down.gif" /> <a href="#hup">Restart Now</a></li> 46<li><img alt="" src="./images/down.gif" /> <a href="#gracefulstop">Graceful Stop</a></li> 47</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> 48<div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> 49<div class="section"> 50<h2><a name="introduction" id="introduction">Introduction</a></h2> 51 52 <p>In order to stop or restart the Apache HTTP Server, you must send a signal to 53 the running <code class="program"><a href="./programs/httpd.html">httpd</a></code> processes. There are two ways to 54 send the signals. First, you can use the unix <code>kill</code> 55 command to directly send signals to the processes. You will 56 notice many <code class="program"><a href="./programs/httpd.html">httpd</a></code> executables running on your system, 57 but you should not send signals to any of them except the parent, 58 whose pid is in the <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code>. That is to say you 59 shouldn't ever need to send signals to any process except the 60 parent. There are four signals that you can send the parent: 61 <code><a href="#term">TERM</a></code>, 62 <code><a href="#graceful">USR1</a></code>, 63 <code><a href="#hup">HUP</a></code>, and 64 <code><a href="#gracefulstop">WINCH</a></code>, which 65 will be described in a moment.</p> 66 67 <p>To send a signal to the parent you should issue a command 68 such as:</p> 69 70<div class="example"><p><code>kill -TERM `cat /usr/local/apache2/logs/httpd.pid`</code></p></div> 71 72 <p>The second method of signaling the <code class="program"><a href="./programs/httpd.html">httpd</a></code> processes 73 is to use the <code>-k</code> command line options: <code>stop</code>, 74 <code>restart</code>, <code>graceful</code> and <code>graceful-stop</code>, 75 as described below. These are arguments to the <code class="program"><a href="./programs/httpd.html">httpd</a></code> binary, but we recommend that 76 you send them using the <code class="program"><a href="./programs/apachectl.html">apachectl</a></code> control script, which 77 will pass them through to <code class="program"><a href="./programs/httpd.html">httpd</a></code>.</p> 78 79 <p>After you have signaled <code class="program"><a href="./programs/httpd.html">httpd</a></code>, you can read about 80 its progress by issuing:</p> 81 82<div class="example"><p><code>tail -f /usr/local/apache2/logs/error_log</code></p></div> 83 84 <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> 85</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> 86<div class="section"> 87<h2><a name="term" id="term">Stop Now</a></h2> 88 89<dl><dt>Signal: TERM</dt> 90<dd><code>apachectl -k stop</code></dd> 91</dl> 92 93 <p>Sending the <code>TERM</code> or <code>stop</code> signal to 94 the parent causes it to immediately attempt to kill off all of its 95 children. It may take it several seconds to complete killing off 96 its children. Then the parent itself exits. Any requests in 97 progress are terminated, and no further requests are served.</p> 98</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> 99<div class="section"> 100<h2><a name="graceful" id="graceful">Graceful Restart</a></h2> 101 102<dl><dt>Signal: USR1</dt> 103<dd><code>apachectl -k graceful</code></dd> 104</dl> 105 106 <p>The <code>USR1</code> or <code>graceful</code> signal causes 107 the parent process to <em>advise</em> the children to exit after 108 their current request (or to exit immediately if they're not 109 serving anything). The parent re-reads its configuration files and 110 re-opens its log files. As each child dies off the parent replaces 111 it with a child from the new <em>generation</em> of the 112 configuration, which begins serving new requests immediately.</p> 113 114 <p>This code is designed to always respect the process control 115 directive of the MPMs, so the number of processes and threads 116 available to serve clients will be maintained at the appropriate 117 values throughout the restart process. Furthermore, it respects 118 <code class="directive"><a href="./mod/mpm_common.html#startservers">StartServers</a></code> in the 119 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 120 been created, then create enough to pick up the slack. Hence the 121 code tries to maintain both the number of children appropriate for 122 the current load on the server, and respect your wishes with the 123 <code class="directive"><a href="./mod/mpm_common.html#startservers">StartServers</a></code> 124 parameter.</p> 125 126 <p>Users of <code class="module"><a href="./mod/mod_status.html">mod_status</a></code> 127 will notice that the server statistics are <strong>not</strong> 128 set to zero when a <code>USR1</code> is sent. The code was 129 written to both minimize the time in which the server is unable 130 to serve new requests (they will be queued up by the operating 131 system, so they're not lost in any event) and to respect your 132 tuning parameters. In order to do this it has to keep the 133 <em>scoreboard</em> used to keep track of all children across 134 generations.</p> 135 136 <p>The status module will also use a <code>G</code> to indicate 137 those children which are still serving requests started before 138 the graceful restart was given.</p> 139 140 <p>At present there is no way for a log rotation script using 141 <code>USR1</code> to know for certain that all children writing 142 the pre-restart log have finished. We suggest that you use a 143 suitable delay after sending the <code>USR1</code> signal 144 before you do anything with the old log. For example if most of 145 your hits take less than 10 minutes to complete for users on 146 low bandwidth links then you could wait 15 minutes before doing 147 anything with the old log.</p> 148 149 <div class="note"> 150 <p>When you issue a restart, a syntax check is first run, to 151 ensure that there are no errors in the configuration files. 152 If your configuration file has errors in it, you will get an 153 error message about that syntax error, and the server will refuse to 154 restart. This avoids the situation where the server halts and then 155 cannot restart, leaving you with a non-functioning server.</p> 156 157 <p>This still will not 158 guarantee that the server will restart correctly. To check the 159 semantics of the configuration files as well as the syntax, you 160 can try starting <code class="program"><a href="./programs/httpd.html">httpd</a></code> as a non-root user. If there 161 are no errors it will attempt to open its sockets and logs and fail 162 because it's not root (or because the currently running 163 <code class="program"><a href="./programs/httpd.html">httpd</a></code> already has those ports bound). If it fails 164 for any other reason then it's probably a config file error and the error 165 should be fixed before issuing the graceful restart.</p></div> 166</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> 167<div class="section"> 168<h2><a name="hup" id="hup">Restart Now</a></h2> 169 170<dl><dt>Signal: HUP</dt> 171<dd><code>apachectl -k restart</code></dd> 172</dl> 173 174 <p>Sending the <code>HUP</code> or <code>restart</code> signal to 175 the parent causes it to kill off its children like in 176 <code>TERM</code>, but the parent doesn't exit. It re-reads its 177 configuration files, and re-opens any log files. Then it spawns a 178 new set of children and continues serving hits.</p> 179 180 <p>Users of <code class="module"><a href="./mod/mod_status.html">mod_status</a></code> 181 will notice that the server statistics are set to zero when a 182 <code>HUP</code> is sent.</p> 183 184<div class="note">As with a graceful restart, a syntax check is run before the 185restart is attempted. If your configuration file has errors in it, the 186restart will not be attempted, and you will receive notification of the 187syntax error(s).</div> 188</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div> 189<div class="section"> 190<h2><a name="gracefulstop" id="gracefulstop">Graceful Stop</a></h2> 191 192<dl><dt>Signal: WINCH</dt> 193<dd><code>apachectl -k graceful-stop</code></dd> 194</dl> 195 196 <p>The <code>WINCH</code> or <code>graceful-stop</code> signal causes 197 the parent process to <em>advise</em> the children to exit after 198 their current request (or to exit immediately if they're not 199 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 200 all ports. The parent will continue to run, and monitor children 201 which are handling requests. Once all children have finalised 202 and exited or the timeout specified by the <code class="directive"><a href="./mod/mpm_common.html#gracefulshutdowntimeout">GracefulShutdownTimeout</a></code> has been 203 reached, the parent will also exit. If the timeout is reached, 204 any remaining children will be sent the <code>TERM</code> signal 205 to force them to exit.</p> 206 207 <p>A <code>TERM</code> signal will immediately terminate the 208 parent process and all children when in the "graceful" state. However 209 as the <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code> will 210 have been removed, you will not be able to use 211 <code>apachectl</code> or <code>httpd</code> to send this signal.</p> 212 213 <div class="note"><p>The <code>graceful-stop</code> signal allows you to run multiple 214 identically configured instances of <code class="program"><a href="./programs/httpd.html">httpd</a></code> at the 215 same time. This is a powerful feature when performing graceful 216 upgrades of httpd, however it can also cause deadlocks and race 217 conditions with some configurations.</p> 218 219 <p>Care has been taken to ensure that on-disk files such as lock files 220 (<code class="directive"><a href="./mod/core.html#mutex">Mutex</a></code>) and Unix socket files 221 (<code class="directive"><a href="./mod/mod_cgid.html#scriptsock">ScriptSock</a></code>) contain the server 222 PID, and should coexist without problem. However, if a configuration 223 directive, third-party module or persistent CGI utilises any other on-disk 224 lock or state files, care should be taken to ensure that multiple running 225 instances of <code class="program"><a href="./programs/httpd.html">httpd</a></code> do not clobber each other's files.</p> 226 227 <p>You should also be wary of other potential race conditions, such as 228 using <code class="program"><a href="./programs/rotatelogs.html">rotatelogs</a></code> style piped logging. Multiple running 229 instances of <code class="program"><a href="./programs/rotatelogs.html">rotatelogs</a></code> attempting to rotate the same 230 logfiles at the same time may destroy each other's logfiles.</p></div> 231</div></div> 232<div class="bottomlang"> 233<p><span>Available Languages: </span><a href="./de/stopping.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> | 234<a href="./en/stopping.html" title="English"> en </a> | 235<a href="./es/stopping.html" hreflang="es" rel="alternate" title="Español"> es </a> | 236<a href="./fr/stopping.html" hreflang="fr" rel="alternate" title="Français"> fr </a> | 237<a href="./ja/stopping.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 238<a href="./ko/stopping.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | 239<a href="./tr/stopping.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p> 240</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> 241<script type="text/javascript"><!--//--><![CDATA[//><!-- 242var comments_shortname = 'httpd'; 243var comments_identifier = 'http://httpd.apache.org/docs/2.4/stopping.html'; 244(function(w, d) { 245 if (w.location.hostname.toLowerCase() == "httpd.apache.org") { 246 d.write('<div id="comments_thread"><\/div>'); 247 var s = d.createElement('script'); 248 s.type = 'text/javascript'; 249 s.async = true; 250 s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier; 251 (d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s); 252 } 253 else { 254 d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>'); 255 } 256})(window, document); 257//--><!]]></script></div><div id="footer"> 258<p class="apache">Copyright 2022 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> 259<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></div><script type="text/javascript"><!--//--><![CDATA[//><!-- 260if (typeof(prettyPrint) !== 'undefined') { 261 prettyPrint(); 262} 263//--><!]]></script> 264</body></html>
