1<?xml version="1.0" encoding="ISO-8859-1"?> 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 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 5 This file is generated from xml source: DO NOT EDIT 6 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 7 --> 8<title>Stopping and Restarting - Apache HTTP Server</title> 9<link href="/style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> 10<link href="/style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> 11<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" /> 12<script src="/style/scripts/prettify.js" type="text/javascript"> 13</script> 14 15<link href="/images/favicon.ico" rel="shortcut icon" /></head> 16<body id="manual-page"><div id="page-header"> 17<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> 18<p class="apache">Apache HTTP Server Version 2.2</p> 19<img alt="" src="/images/feather.gif" /></div> 20<div class="up"><a href="./"><img title="<-" alt="<-" src="/images/left.gif" /></a></div> 21<div id="path"> 22<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 2.2</a></div><div id="page-content"><div id="preamble"><h1>Stopping and Restarting</h1> 23<div class="toplang"> 24<p><span>Available Languages: </span><a href="/de/stopping.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> | 25<a href="/en/stopping.html" title="English"> en </a> | 26<a href="/es/stopping.html" hreflang="es" rel="alternate" title="Espa�ol"> es </a> | 27<a href="/fr/stopping.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> | 28<a href="/ja/stopping.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 29<a href="/ko/stopping.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | 30<a href="/tr/stopping.html" hreflang="tr" rel="alternate" title="T�rk�e"> tr </a></p> 31</div> 32 33 <p>This document covers stopping and restarting Apache on 34 Unix-like systems. Windows NT, 2000 and XP users should see 35 <a href="platform/windows.html#winsvc">Running Apache as a 36 Service</a> and Windows 9x and ME users should see <a href="platform/windows.html#wincons">Running Apache as a 37 Console Application</a> for information on how to control 38 Apache on those platforms.</p> 39</div> 40<div id="quickview"><ul id="toc"><li><img alt="" src="/images/down.gif" /> <a href="#introduction">Introduction</a></li> 41<li><img alt="" src="/images/down.gif" /> <a href="#term">Stop Now</a></li> 42<li><img alt="" src="/images/down.gif" /> <a href="#graceful">Graceful Restart</a></li> 43<li><img alt="" src="/images/down.gif" /> <a href="#hup">Restart Now</a></li> 44<li><img alt="" src="/images/down.gif" /> <a href="#gracefulstop">Graceful Stop</a></li> 45</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></ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div> 46<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 47<div class="section"> 48<h2><a name="introduction" id="introduction">Introduction</a></h2> 49 50 <p>In order to stop or restart Apache, you must send a signal to 51 the running <code class="program"><a href="/programs/httpd.html">httpd</a></code> processes. There are two ways to 52 send the signals. First, you can use the unix <code>kill</code> 53 command to directly send signals to the processes. You will 54 notice many <code class="program"><a href="/programs/httpd.html">httpd</a></code> executables running on your system, 55 but you should not send signals to any of them except the parent, 56 whose pid is in the <code class="directive"><a href="/mod/mpm_common.html#pidfile">PidFile</a></code>. That is to say you 57 shouldn't ever need to send signals to any process except the 58 parent. There are four signals that you can send the parent: 59 <code><a href="#term">TERM</a></code>, 60 <code><a href="#graceful">USR1</a></code>, 61 <code><a href="#hup">HUP</a></code>, and 62 <code><a href="#gracefulstop">WINCH</a></code>, which 63 will be described in a moment.</p> 64 65 <p>To send a signal to the parent you should issue a command 66 such as:</p> 67 68<div class="example"><p><code>kill -TERM `cat /usr/local/apache2/logs/httpd.pid`</code></p></div> 69 70 <p>The second method of signaling the <code class="program"><a href="/programs/httpd.html">httpd</a></code> processes 71 is to use the <code>-k</code> command line options: <code>stop</code>, 72 <code>restart</code>, <code>graceful</code> and <code>graceful-stop</code>, 73 as described below. These are arguments to the <code class="program"><a href="/programs/httpd.html">httpd</a></code> binary, but we recommend that 74 you send them using the <code class="program"><a href="/programs/apachectl.html">apachectl</a></code> control script, which 75 will pass them through to <code class="program"><a href="/programs/httpd.html">httpd</a></code>.</p> 76 77 <p>After you have signaled <code class="program"><a href="/programs/httpd.html">httpd</a></code>, you can read about 78 its progress by issuing:</p> 79 80<div class="example"><p><code>tail -f /usr/local/apache2/logs/error_log</code></p></div> 81 82 <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> 83</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 84<div class="section"> 85<h2><a name="term" id="term">Stop Now</a></h2> 86 87<dl><dt>Signal: TERM</dt> 88<dd><code>apachectl -k stop</code></dd> 89</dl> 90 91 <p>Sending the <code>TERM</code> or <code>stop</code> signal to 92 the parent causes it to immediately attempt to kill off all of its 93 children. It may take it several seconds to complete killing off 94 its children. Then the parent itself exits. Any requests in 95 progress are terminated, and no further requests are served.</p> 96</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 97<div class="section"> 98<h2><a name="graceful" id="graceful">Graceful Restart</a></h2> 99 100<dl><dt>Signal: USR1</dt> 101<dd><code>apachectl -k graceful</code></dd> 102</dl> 103 104 <p>The <code>USR1</code> or <code>graceful</code> signal causes 105 the parent process to <em>advise</em> the children to exit after 106 their current request (or to exit immediately if they're not 107 serving anything). The parent re-reads its configuration files and 108 re-opens its log files. As each child dies off the parent replaces 109 it with a child from the new <em>generation</em> of the 110 configuration, which begins serving new requests immediately.</p> 111 112 <p>This code is designed to always respect the process control 113 directive of the MPMs, so the number of processes and threads 114 available to serve clients will be maintained at the appropriate 115 values throughout the restart process. Furthermore, it respects 116 <code class="directive"><a href="/mod/mpm_common.html#startservers">StartServers</a></code> in the 117 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 118 been created, then create enough to pick up the slack. Hence the 119 code tries to maintain both the number of children appropriate for 120 the current load on the server, and respect your wishes with the 121 <code class="directive"><a href="/mod/mpm_common.html#startservers">StartServers</a></code> 122 parameter.</p> 123 124 <p>Users of <code class="module"><a href="/mod/mod_status.html">mod_status</a></code> 125 will notice that the server statistics are <strong>not</strong> 126 set to zero when a <code>USR1</code> is sent. The code was 127 written to both minimize the time in which the server is unable 128 to serve new requests (they will be queued up by the operating 129 system, so they're not lost in any event) and to respect your 130 tuning parameters. In order to do this it has to keep the 131 <em>scoreboard</em> used to keep track of all children across 132 generations.</p> 133 134 <p>The status module will also use a <code>G</code> to indicate 135 those children which are still serving requests started before 136 the graceful restart was given.</p> 137 138 <p>At present there is no way for a log rotation script using 139 <code>USR1</code> to know for certain that all children writing 140 the pre-restart log have finished. We suggest that you use a 141 suitable delay after sending the <code>USR1</code> signal 142 before you do anything with the old log. For example if most of 143 your hits take less than 10 minutes to complete for users on 144 low bandwidth links then you could wait 15 minutes before doing 145 anything with the old log.</p> 146 147 <div class="note">If your configuration file has errors 148 in it when you issue a restart then your parent will not 149 restart, it will exit with an error. In the case of graceful 150 restarts it will also leave children running when it exits. 151 (These are the children which are "gracefully exiting" by 152 handling their last request.) This will cause problems if you 153 attempt to restart the server -- it will not be able to bind to 154 its listening ports. Before doing a restart, you can check the 155 syntax of the configuration files with the <code>-t</code> 156 command line argument (see <code class="program"><a href="/programs/httpd.html">httpd</a></code>). This still will not 157 guarantee that the server will restart correctly. To check the 158 semantics of the configuration files as well as the syntax, you 159 can try starting <code class="program"><a href="/programs/httpd.html">httpd</a></code> as a non-root user. If there 160 are no errors it will attempt to open its sockets and logs and fail 161 because it's not root (or because the currently running 162 <code class="program"><a href="/programs/httpd.html">httpd</a></code> already has those ports bound). If it fails 163 for any other reason then it's probably a config file error and the error 164 should be fixed before issuing the graceful restart.</div> 165</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 166<div class="section"> 167<h2><a name="hup" id="hup">Restart Now</a></h2> 168 169<dl><dt>Signal: HUP</dt> 170<dd><code>apachectl -k restart</code></dd> 171</dl> 172 173 <p>Sending the <code>HUP</code> or <code>restart</code> signal to 174 the parent causes it to kill off its children like in 175 <code>TERM</code>, but the parent doesn't exit. It re-reads its 176 configuration files, and re-opens any log files. Then it spawns a 177 new set of children and continues serving hits.</p> 178 179 <p>Users of <code class="module"><a href="/mod/mod_status.html">mod_status</a></code> 180 will notice that the server statistics are set to zero when a 181 <code>HUP</code> is sent.</p> 182 183<div class="note">If your configuration file has errors in it when you issue a 184restart then your parent will not restart, it will exit with an 185error. See above for a method of avoiding this.</div> 186</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 187<div class="section"> 188<h2><a name="gracefulstop" id="gracefulstop">Graceful Stop</a></h2> 189 190<dl><dt>Signal: WINCH</dt> 191<dd><code>apachectl -k graceful-stop</code></dd> 192</dl> 193 194 <p>The <code>WINCH</code> or <code>graceful-stop</code> signal causes 195 the parent process to <em>advise</em> the children to exit after 196 their current request (or to exit immediately if they're not 197 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 198 all ports. The parent will continue to run, and monitor children 199 which are handling requests. Once all children have finalised 200 and exited or the timeout specified by the <code class="directive"><a href="/mod/mpm_common.html#gracefulshutdowntimeout">GracefulShutdownTimeout</a></code> has been 201 reached, the parent will also exit. If the timeout is reached, 202 any remaining children will be sent the <code>TERM</code> signal 203 to force them to exit.</p> 204 205 <p>A <code>TERM</code> signal will immediately terminate the 206 parent process and all children when in the "graceful" state. However 207 as the <code class="directive"><a href="/mod/mpm_common.html#pidfile">PidFile</a></code> will 208 have been removed, you will not be able to use 209 <code>apachectl</code> or <code>httpd</code> to send this signal.</p> 210 211 <div class="note"><p>The <code>graceful-stop</code> signal allows you to run multiple 212 identically configured instances of <code class="program"><a href="/programs/httpd.html">httpd</a></code> at the 213 same time. This is a powerful feature when performing graceful 214 upgrades of Apache, however it can also cause deadlocks and race 215 conditions with some configurations.</p> 216 217 <p>Care has been taken to ensure that on-disk files 218 such as the <code class="directive"><a href="/mod/mpm_common.html#lockfile">Lockfile</a></code> and <code class="directive"><a href="/mod/mod_cgid.html#scriptsock">ScriptSock</a></code> files contain the server 219 PID, and should coexist without problem. However, if a configuration 220 directive, third-party module or persistent CGI utilises any other on-disk 221 lock or state files, care should be taken to ensure that multiple running 222 instances of <code class="program"><a href="/programs/httpd.html">httpd</a></code> do not clobber each others files.</p> 223 224 <p>You should also be wary of other potential race conditions, such as 225 using <code class="program"><a href="/programs/rotatelogs.html">rotatelogs</a></code> style piped logging. Multiple running 226 instances of <code class="program"><a href="/programs/rotatelogs.html">rotatelogs</a></code> attempting to rotate the same 227 logfiles at the same time may destroy each other's logfiles.</p></div> 228</div></div> 229<div class="bottomlang"> 230<p><span>Available Languages: </span><a href="/de/stopping.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> | 231<a href="/en/stopping.html" title="English"> en </a> | 232<a href="/es/stopping.html" hreflang="es" rel="alternate" title="Espa�ol"> es </a> | 233<a href="/fr/stopping.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> | 234<a href="/ja/stopping.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 235<a href="/ko/stopping.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> | 236<a href="/tr/stopping.html" hreflang="tr" rel="alternate" title="T�rk�e"> tr </a></p> 237</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. 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