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diff --git a/docs/manual/stopping.html.en b/docs/manual/stopping.html.en deleted file mode 100644 index 783d1c0250..0000000000 --- a/docs/manual/stopping.html.en +++ /dev/null @@ -1,183 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> -<HTML> -<HEAD> -<TITLE>Stopping and Restarting Apache</TITLE> -</HEAD> - -<!-- Background white, links blue (unvisited), navy (visited), red (active) --> -<BODY - BGCOLOR="#FFFFFF" - TEXT="#000000" - LINK="#0000FF" - VLINK="#000080" - ALINK="#FF0000" -> -<!--#include virtual="header.html" --> -<H1 ALIGN="CENTER">Stopping and Restarting Apache</H1> - -<P>This document covers stopping and restarting Apache on Unix -only. Windows users should see <A HREF="windows.html#signal">Signalling -Apache when running</A>.</P> - -<P>You will notice many <CODE>httpd</CODE> executables running on your system, -but you should not send signals to any of them except the parent, whose -pid is in the <A HREF="mod/core.html#pidfile">PidFile</A>. That is to -say you shouldn't ever need to send signals to any process except the -parent. There are three signals that you can send the parent: -<CODE>TERM</CODE>, <CODE>HUP</CODE>, and <CODE>USR1</CODE>, which will -be described in a moment. - -<P>To send a signal to the parent you should issue a command such as: -<BLOCKQUOTE><PRE> - kill -TERM `cat /usr/local/apache/logs/httpd.pid` -</PRE></BLOCKQUOTE> - -You can read about its progress by issuing: - -<BLOCKQUOTE><PRE> - tail -f /usr/local/apache/logs/error_log -</PRE></BLOCKQUOTE> - -Modify those examples to match your -<A HREF="mod/core.html#serverroot">ServerRoot</A> and -<A HREF="mod/core.html#pidfile">PidFile</A> settings. - -<P>As of Apache 1.3 we provide a script <CODE>src/support/apachectl</CODE> -which can be used to start, stop, and restart Apache. It may need a -little customization for your system, see the comments at the top of -the script. - -<H3>TERM Signal: stop now</H3> - -<P>Sending the <CODE>TERM</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. - -<H3>HUP Signal: restart now</H3> - -<P>Sending the <CODE>HUP</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>Users of the -<A HREF="mod/mod_status.html">status module</A> -will notice that the server statistics are -set to zero when a <CODE>HUP</CODE> is sent. - -<P><STRONG>Note:</STRONG> If your configuration file has errors in it when -you issue a -restart then your parent will not restart, it will exit with an error. -See below for a method of avoiding this. - -<H3>USR1 Signal: graceful restart</H3> - -<P><STRONG>Note:</STRONG> prior to release 1.2b9 this code is quite unstable -and shouldn't be used at all. - -<P>The <CODE>USR1</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>This code is designed to always respect the -<A HREF="mod/core.html#maxclients">MaxClients</A>, -<A HREF="mod/core.html#minspareservers">MinSpareServers</A>, -and <A HREF="mod/core.html#maxspareservers">MaxSpareServers</A> settings. -Furthermore, it respects <A HREF="mod/core.html#startservers">StartServers</A> -in the following manner: if after one second at least StartServers new -children have not been created, then create enough to pick up the slack. -This is to say that the code tries to maintain both the number of children -appropriate for the current load on the server, and respect your wishes -with the StartServers parameter. - -<P>Users of the -<A HREF="mod/mod_status.html">status module</A> -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>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>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><STRONG>Note:</STRONG> If your configuration file has errors in it when -you issue a -restart then your parent will not restart, it will exit with an error. -In the case of graceful -restarts it will also leave children running when it exits. (These are -the children which are "gracefully exiting" by handling their last request.) -This will cause problems if you attempt to restart the server -- it will -not be able to bind to its listening ports. Before doing a restart, you -can check the syntax of the configuration files with the <CODE>-t</CODE> -command line argument (see <A HREF="invoking.html">Starting -Apache</A>). 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 httpd 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 httpd -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. - - -<H3>Appendix: signals and race conditions</H3> - -<P>Prior to Apache 1.2b9 there were several <EM>race conditions</EM> -involving the restart and die signals (a simple description of race -condition is: a time-sensitive problem, as in if something happens at just -the wrong time it won't behave as expected). For those architectures that -have the "right" feature set we have eliminated as many as we can. -But it should be noted that there still do exist race conditions on -certain architectures. - -<P>Architectures that use an on disk -<A HREF="mod/core.html#scoreboardfile">ScoreBoardFile</A> -have the potential to corrupt their scoreboards. This can result in -the "bind: Address already in use" (after <CODE>HUP</CODE>) or -"long lost child came home!" (after <CODE>USR1</CODE>). The former is -a fatal error, while the latter just causes the server to lose a scoreboard -slot. So it might be advisable to use graceful restarts, with -an occasional hard restart. These problems are very difficult to work -around, but fortunately most architectures do not require a scoreboard file. -See the ScoreBoardFile documentation for a method to determine if your -architecture uses it. - -<P><CODE>NEXT</CODE> and <CODE>MACHTEN</CODE> (68k only) have small race -conditions -which can cause a restart/die signal to be lost, but should not cause the -server to do anything otherwise problematic. -<!-- they don't have sigaction, or we're not using it -djg --> - -<P>All architectures have a small race condition in each child involving -the second and subsequent requests on a persistent HTTP connection -(KeepAlive). It may exit after reading the request line but before -reading any of the request headers. There is a fix that was discovered -too late to make 1.2. In theory this isn't an issue because the KeepAlive -client has to expect these events because of network latencies and -server timeouts. In practice it doesn't seem to affect anything either --- in a test case the server was restarted twenty times per second and -clients successfully browsed the site without getting broken images or -empty documents. - -<!--#include virtual="footer.html" --> -</BODY> -</HTML> |