From: Joshua Slive Date: Thu, 21 Dec 2000 05:38:28 +0000 (+0000) Subject: A few small changes to bring this up to 2.0. X-Git-Tag: APACHE_2_0_BETA_CANDIDATE_1~352 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=dd229e9515555e92015b52d3bc4bd50c329cfdff;p=apache A few small changes to bring this up to 2.0. This doc could use a major rewrite. git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@87487 13f79535-47bb-0310-9956-ffa450edef68 --- diff --git a/docs/manual/stopping.html b/docs/manual/stopping.html index 12604562a7..ed75c8a092 100644 --- a/docs/manual/stopping.html +++ b/docs/manual/stopping.html @@ -1,7 +1,7 @@ -Stopping and Restarting Apache +Stopping and Restarting the Server @@ -13,11 +13,12 @@ ALINK="#FF0000" > -

Stopping and Restarting Apache

+

Stopping and Restarting the Server

-

This document covers stopping and restarting Apache on Unix -only. Windows users should see Signalling -Apache when running.

+

This document covers stopping and restarting Apache on Unix-like +systems. Windows users should see Signalling Apache when +running.

You will notice many httpd executables running on your system, but you should not send signals to any of them except the parent, whose @@ -42,12 +43,15 @@ Modify those examples to match your ServerRoot and PidFile settings. -

As of Apache 1.3 we provide a script src/support/apachectl -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. +

A shell script called apachectl is provided +which automates the processing of signalling Apache. +For details about this script, see the documentation +on starting Apache.

-

TERM Signal: stop now

+

Stop Now

+ +

Signal: TERM
+apachectl stop

Sending the TERM signal to the parent causes it to immediately attempt to kill off all of its children. It may take it @@ -55,46 +59,29 @@ 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. -

HUP Signal: restart now

- -

Sending the HUP signal to the parent causes it to kill off -its children like in TERM 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. - -

Users of the -status module -will notice that the server statistics are -set to zero when a HUP is sent. - -

Note: 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. - -

USR1 Signal: graceful restart

+

Graceful Restart

-

Note: prior to release 1.2b9 this code is quite unstable -and shouldn't be used at all. +

Signal: WINCH
+apachectl graceful

-

The USR1 signal causes the parent process to advise +

The WINCH signal causes the parent process to advise 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 generation of the -configuration, which begins serving new requests immediately. - -

This code is designed to always respect the -MaxClients, -MinSpareServers, -and MaxSpareServers settings. -Furthermore, it respects StartServers -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. +configuration, which begins serving new requests immediately.

+ +

This code is designed to always respect the MaxClients, MinSpareServers, and MaxSpareServers +settings. Furthermore, it respects StartServers 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.

Users of the status module @@ -112,33 +99,54 @@ children which are still serving requests started before the graceful restart was given.

At present there is no way for a log rotation script using -USR1 to know for certain that all children writing the +WINCH 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 USR1 signal before you do anything with the +after sending the WINCH 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. -

Note: 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 -t +

Note: 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 -t command line argument (see Starting -Apache). 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 +Apache). 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. +

Restart Now

+ +

Signal: HUP
+apachectl restart

+ +

Sending the HUP signal to the parent causes it to kill off +its children like in TERM 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. + +

Users of the +status module +will notice that the server statistics are +set to zero when a HUP is sent. + +

Note: 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. + +

Appendix: signals and race conditions

Prior to Apache 1.2b9 there were several race conditions diff --git a/docs/manual/stopping.html.en b/docs/manual/stopping.html.en index 12604562a7..ed75c8a092 100644 --- a/docs/manual/stopping.html.en +++ b/docs/manual/stopping.html.en @@ -1,7 +1,7 @@ -Stopping and Restarting Apache +Stopping and Restarting the Server @@ -13,11 +13,12 @@ ALINK="#FF0000" > -

Stopping and Restarting Apache

+

Stopping and Restarting the Server

-

This document covers stopping and restarting Apache on Unix -only. Windows users should see Signalling -Apache when running.

+

This document covers stopping and restarting Apache on Unix-like +systems. Windows users should see Signalling Apache when +running.

You will notice many httpd executables running on your system, but you should not send signals to any of them except the parent, whose @@ -42,12 +43,15 @@ Modify those examples to match your ServerRoot and PidFile settings. -

As of Apache 1.3 we provide a script src/support/apachectl -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. +

A shell script called apachectl is provided +which automates the processing of signalling Apache. +For details about this script, see the documentation +on starting Apache.

-

TERM Signal: stop now

+

Stop Now

+ +

Signal: TERM
+apachectl stop

Sending the TERM signal to the parent causes it to immediately attempt to kill off all of its children. It may take it @@ -55,46 +59,29 @@ 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. -

HUP Signal: restart now

- -

Sending the HUP signal to the parent causes it to kill off -its children like in TERM 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. - -

Users of the -status module -will notice that the server statistics are -set to zero when a HUP is sent. - -

Note: 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. - -

USR1 Signal: graceful restart

+

Graceful Restart

-

Note: prior to release 1.2b9 this code is quite unstable -and shouldn't be used at all. +

Signal: WINCH
+apachectl graceful

-

The USR1 signal causes the parent process to advise +

The WINCH signal causes the parent process to advise 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 generation of the -configuration, which begins serving new requests immediately. - -

This code is designed to always respect the -MaxClients, -MinSpareServers, -and MaxSpareServers settings. -Furthermore, it respects StartServers -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. +configuration, which begins serving new requests immediately.

+ +

This code is designed to always respect the MaxClients, MinSpareServers, and MaxSpareServers +settings. Furthermore, it respects StartServers 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.

Users of the status module @@ -112,33 +99,54 @@ children which are still serving requests started before the graceful restart was given.

At present there is no way for a log rotation script using -USR1 to know for certain that all children writing the +WINCH 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 USR1 signal before you do anything with the +after sending the WINCH 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. -

Note: 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 -t +

Note: 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 -t command line argument (see Starting -Apache). 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 +Apache). 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. +

Restart Now

+ +

Signal: HUP
+apachectl restart

+ +

Sending the HUP signal to the parent causes it to kill off +its children like in TERM 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. + +

Users of the +status module +will notice that the server statistics are +set to zero when a HUP is sent. + +

Note: 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. + +

Appendix: signals and race conditions

Prior to Apache 1.2b9 there were several race conditions