mpm_common.xml revision 61de37121fdb85afc120ce4f95602a13dfd110f4
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<!DOCTYPE modulesynopsis SYSTEM "/style/modulesynopsis.dtd">
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<?xml-stylesheet type="text/xsl" href="/style/manual.en.xsl"?>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<!-- $LastChangedRevision$ -->
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bd8e360cd1db83dcb2694ea9122ce3bc5bae678avboxsync (the "License"); you may not use this file except in compliance with
bd8e360cd1db83dcb2694ea9122ce3bc5bae678avboxsync the License. You may obtain a copy of the License at
bd8e360cd1db83dcb2694ea9122ce3bc5bae678avboxsync Unless required by applicable law or agreed to in writing, software
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bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<description>A collection of directives that are implemented by
23179f1443b03947d85eccc81cbc6b5153a4abf3vboxsyncmore than one multi-processing module (MPM)</description>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<description>Directory where Apache HTTP Server attempts to
bff1915a855c5b71d76f6391549eadda348e33b0vboxsyncswitch before dumping core</description>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<syntax>CoreDumpDirectory <var>directory</var></syntax>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<default>See usage for the default setting</default>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<contextlist><context>server config</context></contextlist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<modulelist><module>event</module><module>prefork</module>
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync <p>This controls the directory to which Apache httpd attempts to
0f299115229ed1bfd92c030c82b8f9930f109f2dvboxsync switch before dumping core. If your operating system is configured to
5eabf773597082761832bc0a32b3660e8771f9f1vboxsync create core files in the working directory of the crashing process,
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <directive>CoreDumpDirectory</directive> is necessary to change working
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync directory from the default <directive module="core">ServerRoot</directive>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync directory, which should not be writable by the user the server runs as.</p>
e165c61901edef5d42ef72ba30880eb3074e435dvboxsync <p>If you want a core dump for debugging, you can use this directive to
a649440589a732fe4aad2af224cc72318108d855vboxsync place it in a different location. This directive has no effect if your
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync operating system is not configured to write core files to the working directory
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync of the crashing processes.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>If Apache httpd starts as root and switches to another user, the
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync Linux kernel <em>disables</em> core dumps even if the directory is
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync writable for the process. Apache httpd (2.0.46 and later) reenables core dumps
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync on Linux 2.4 and beyond, but only if you explicitly configure a <directive
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync <p>To enable core-dumping of suid-executables on BSD-systems (such
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync as FreeBSD), set <code>kern.sugid_coredump</code> to 1.
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p><directive>CoreDumpDirectory</directive> processing only occurs for
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync a select set of fatal signals: SIGFPE, SIGILL, SIGABORT,
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync SIGSEGV, and SIGBUS.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>On some operating systems, SIGQUIT also results in a core dump but
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync does not go through <directive>CoreDumpDirectory</directive> or
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync <directive>EnableExceptionHook</directive> processing, so the core
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync location is dictated entirely by the operating system.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<description>Enables a hook that runs exception handlers
bff1915a855c5b71d76f6391549eadda348e33b0vboxsyncafter a crash</description>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<contextlist><context>server config</context></contextlist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<modulelist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<compatibility>Available in version 2.0.49 and later</compatibility>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>For safety reasons this directive is only available if the server was
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync configured with the <code>--enable-exception-hook</code> option. It
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync enables a hook that allows external modules to plug in and do something
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync after a child crashed.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>There are already two modules, <code>mod_whatkilledus</code> and
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync <code>mod_backtrace</code> that make use of this hook. Please have a
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync look at Jeff Trawick's <a
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync href="http://www.apache.org/~trawick/exception_hook.html"
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync >EnableExceptionHook site</a> for more information about these.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</directivesynopsis>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<directivesynopsis>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<description>Specify a timeout after which a gracefully shutdown server
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsyncwill exit.</description>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<syntax>GracefulShutDownTimeout <var>seconds</var></syntax>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<contextlist><context>server config</context></contextlist>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<modulelist><module>prefork</module><module>worker</module>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<compatibility>Available in version 2.2 and later</compatibility>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync <p>The <directive>GracefulShutdownTimeout</directive> specifies
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync how many seconds after receiving a "graceful-stop" signal, a
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync server should continue to run, handling the existing connections.</p>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync <p>Setting this value to zero means that the server will wait
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync indefinitely until all remaining requests have been fully served.</p>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync</directivesynopsis>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<directivesynopsis>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<description>File where the server records the process ID
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsyncof the daemon</description>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<contextlist><context>server config</context></contextlist>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<modulelist><module>event</module><module>mpm_winnt</module>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<module>mpmt_os2</module><module>prefork</module><module>worker</module>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync</modulelist>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync <p>The <directive>PidFile</directive> directive sets the file to
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync which the server records the process id of the daemon. If the
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync filename is not absolute then it is assumed to be relative to the
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync <directive module="core">ServerRoot</directive>.</p>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync <p>It is often useful to be able to send the server a signal,
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync so that it closes and then re-opens its <directive
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync module="mod_log_config">TransferLog</directive>, and
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync re-reads its configuration files. This is done by sending a
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync SIGHUP (kill -1) signal to the process id listed in the
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync <p>The <directive>PidFile</directive> is subject to the same
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync warnings about log file placement and <a
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync href="/misc/security_tips.html#serverroot">security</a>.</p>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync <p>As of Apache HTTP Server 2, we recommended that you only use the <program>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync apachectl</program> script, or the init script that your OS provides,
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync for (re-)starting or stopping the server.</p>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync</directivesynopsis>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<directivesynopsis>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<description>IP addresses and ports that the server
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsynclistens to</description>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<syntax>Listen [<var>IP-address</var>:]<var>portnumber</var> [<var>protocol</var>]</syntax>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<contextlist><context>server config</context></contextlist>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<modulelist><module>mpm_netware</module><module>mpm_winnt</module>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync</modulelist>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<compatibility>Required directive since Apache HTTP Server 2.0<br/>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsyncThe <var>protocol</var> argument was added in 2.1.5</compatibility>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync <p>The <directive>Listen</directive> directive instructs Apache httpd to
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync listen to only specific IP addresses or ports; by default it
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync responds to requests on all IP interfaces. <directive>Listen</directive>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync is now a required directive. If it is not in the config file, the
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync server will fail to start. This is a change from previous versions
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync of Apache httpd.</p>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync <p>The <directive>Listen</directive> directive tells the server to
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync accept incoming requests on the specified port or address-and-port
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync combination. If only a port number is specified, the server listens to
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync the given port on all interfaces. If an IP address is given as well
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync as a port, the server will listen on the given port and
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync interface.</p>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync <p>Multiple <directive>Listen</directive> directives may be used to
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync specify a number of addresses and ports to listen to. The server will
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync respond to requests from any of the listed addresses and ports.</p>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync <p>For example, to make the server accept connections on both
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync port 80 and port 8000, use:</p>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync Listen 80<br />
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync Listen 8000
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync <p>To make the server accept connections on two specified
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync interfaces and port numbers, use </p>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync Listen 192.170.2.1:80<br />
202a3bbf6be480c96c9dd320ebf876f9182fc81evboxsync Listen 192.170.2.5:8000
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync <p>IPv6 addresses must be surrounded in square brackets, as in the
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync following example:</p>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync Listen [2001:db8::a00:20ff:fea7:ccea]:80
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync <p>The optional <var>protocol</var> argument is not required for most
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync configurations. If not specified, <code>https</code> is the default for
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync port 443 and <code>http</code> the default for all other ports. The
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync protocol is used to determine which module should handle a request, and
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync to apply protocol specific optimizations with the
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync <directive module="core">AcceptFilter</directive> directive.</p>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync <p>You only need to set the protocol if you are running on non-standard
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync ports. For example, running an <code>https</code> site on port 8443:</p>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync Listen 192.170.2.1:8443 https
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync Multiple <directive>Listen</directive> directives for the same ip
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync address and port will result in an <code>Address already in use</code>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync error message.
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync<seealso><a href="/dns-caveats.html">DNS Issues</a></seealso>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync<seealso><a href="/bind.html">Setting which addresses and ports Apache HTTP Server
fab913c70075c45e1c617edd1dce89b88a45936dvboxsynchref="http://wiki.apache.org/httpd/CouldNotBindToAddress">Further
fab913c70075c45e1c617edd1dce89b88a45936dvboxsyncdiscussion of the <code>Address already in use</code> error message,
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync</directivesynopsis>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync<directivesynopsis>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync<description>Maximum length of the queue of pending connections</description>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<contextlist><context>server config</context></contextlist>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<modulelist>
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync<module>mpm_netware</module><module>mpm_winnt</module>
fab913c70075c45e1c617edd1dce89b88a45936dvboxsync <p>The maximum length of the queue of pending connections.
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync Generally no tuning is needed or desired, however on some
9c422943cda5afa926d367aeb7d40cfdffa216f9vboxsync systems it is desirable to increase this when under a TCP SYN
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync flood attack. See the backlog parameter to the
0ce6ae9d6efed5d54222a13bbdabce9e688e4447vboxsync <p>This will often be limited to a smaller number by the
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync operating system. This varies from OS to OS. Also note that
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync many OSes do not use exactly what is specified as the backlog,
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync but use a number based on (but normally larger than) what is
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<description>Maximum number of connections that will be processed
bff1915a855c5b71d76f6391549eadda348e33b0vboxsyncsimultaneously</description>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<contextlist><context>server config</context></contextlist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<modulelist><module>event</module><module>prefork</module>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</modulelist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>The <directive>MaxClients</directive> directive sets the limit
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync on the number of simultaneous requests that will be served. Any
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync connection attempts over the <directive>MaxClients</directive>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync limit will normally be queued, up to a number based on the
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <directive module="mpm_common">ListenBacklog</directive>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync directive. Once a child process is freed at the end of a different
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync request, the connection will then be serviced.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>For non-threaded servers (<em>i.e.</em>, <module>prefork</module>),
d056279b935642d0fc1ddf89c17cab3bc6c30b83vboxsync <directive>MaxClients</directive> translates into the maximum
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync number of child processes that will be launched to serve requests.
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync The default value is <code>256</code>; to increase it, you must also raise
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync <directive module="mpm_common">ServerLimit</directive>.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>For threaded and hybrid servers (<em>e.g.</em> <module>event</module>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync or <module>worker</module>) <directive>MaxClients</directive> restricts
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync the total number of threads that will be available to serve clients.
18b7c7af4829f4a9add1d070499b96b8e1e96fdbvboxsync For hybrid MPMs the default value is <code>16</code> (<directive
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync module="mpm_common">ServerLimit</directive>) multiplied by the value of
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync >ThreadsPerChild</directive>). Therefore, to increase <directive
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync >MaxClients</directive> to a value that requires more than 16 processes,
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<description>Maximum amount of memory that the main allocator is allowed
bff1915a855c5b71d76f6391549eadda348e33b0vboxsyncto hold without calling <code>free()</code></description>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<contextlist><context>server config</context></contextlist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<modulelist><module>event</module><module>mpm_netware</module>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<module>prefork</module><module>worker</module><module>mpm_winnt</module>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</modulelist>
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync <p>The <directive>MaxMemFree</directive> directive sets the
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync maximum number of free Kbytes that the main allocator is allowed
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync to hold without calling <code>free()</code>. When not set, or when set
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync to zero, the threshold will be set to unlimited.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<description>Limit on the number of connections that an individual child server
bff1915a855c5b71d76f6391549eadda348e33b0vboxsyncwill handle during its life</description>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<syntax>MaxConnectionsPerChild <var>number</var></syntax>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<contextlist><context>server config</context></contextlist>
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync<modulelist><module>event</module><module>mpm_netware</module>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<module>prefork</module><module>worker</module></modulelist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<compatibility>Available Apache HTTP Server 2.3.9 and later. The old name
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<code>MaxRequestsPerChild</code> is still supported.</compatibility>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>The <directive>MaxConnectionsPerChild</directive> directive sets
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync the limit on the number of connections that an individual child
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync server process will handle. After
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync <directive>MaxConnectionsPerChild</directive> connections, the child
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync process will die. If <directive>MaxConnectionsPerChild</directive> is
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <code>0</code>, then the process will never expire.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>Setting <directive>MaxConnectionsPerChild</directive> to a
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync non-zero value limits the amount of memory that process can consume
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync by (accidental) memory leakage.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</directivesynopsis>
aa0632eb844172ced4bef7b3afdbb216c8462fb2vboxsync<directivesynopsis>
aa0632eb844172ced4bef7b3afdbb216c8462fb2vboxsync<description>Maximum number of idle threads</description>
aa0632eb844172ced4bef7b3afdbb216c8462fb2vboxsync<contextlist><context>server config</context></contextlist>
aa0632eb844172ced4bef7b3afdbb216c8462fb2vboxsync<modulelist><module>event</module><module>mpm_netware</module>
aa0632eb844172ced4bef7b3afdbb216c8462fb2vboxsync<module>mpmt_os2</module><module>worker</module></modulelist>
aa0632eb844172ced4bef7b3afdbb216c8462fb2vboxsync <p>Maximum number of idle threads. Different MPMs deal with this
432d08d68b9683d01880890d475a4cadd84b69cevboxsync directive differently.</p>
432d08d68b9683d01880890d475a4cadd84b69cevboxsync <code>MaxSpareThreads 250</code>. This MPM deals with idle threads
432d08d68b9683d01880890d475a4cadd84b69cevboxsync on a server-wide basis. If there are too many idle threads in the
432d08d68b9683d01880890d475a4cadd84b69cevboxsync server then child processes are killed until the number of idle
432d08d68b9683d01880890d475a4cadd84b69cevboxsync threads is less than this number.</p>
432d08d68b9683d01880890d475a4cadd84b69cevboxsync <code>MaxSpareThreads 100</code>. Since this MPM runs a
432d08d68b9683d01880890d475a4cadd84b69cevboxsync single-process, the spare thread count is also server-wide.</p>
aa0632eb844172ced4bef7b3afdbb216c8462fb2vboxsync <module>mpmt_os2</module> the default value is <code>10</code>.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>The range of the <directive>MaxSpareThreads</directive> value
e214bb78026c1d64078b34ca9504d3f5abbc52efvboxsync is restricted. Apache httpd will correct the given value automatically
e214bb78026c1d64078b34ca9504d3f5abbc52efvboxsync according to the following rules:</p>
e214bb78026c1d64078b34ca9504d3f5abbc52efvboxsync <li><module>mpm_netware</module> wants the value to be greater than
e214bb78026c1d64078b34ca9504d3f5abbc52efvboxsync <directive module="mpm_common">MinSpareThreads</directive>.</li>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <li>For <module>worker</module>, the value must be greater or equal
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync to the sum of <directive module="mpm_common">MinSpareThreads</directive>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync and <directive module="mpm_common">ThreadsPerChild</directive>.</li>
fc148a6b23d25a87561beaffe0ba06c3ba93bf5avboxsync<seealso><directive module="mpm_common">MinSpareThreads</directive></seealso>
fc148a6b23d25a87561beaffe0ba06c3ba93bf5avboxsync<seealso><directive module="mpm_common">StartServers</directive></seealso>
6e12ccc60ac657fb87e27b7a2b26e0a63bebe024vboxsync<seealso><directive module="prefork">MaxSpareServers</directive></seealso>
6e12ccc60ac657fb87e27b7a2b26e0a63bebe024vboxsync</directivesynopsis>
6e12ccc60ac657fb87e27b7a2b26e0a63bebe024vboxsync<directivesynopsis>
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync<description>Minimum number of idle threads available to handle request
bff1915a855c5b71d76f6391549eadda348e33b0vboxsyncspikes</description>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<contextlist><context>server config</context></contextlist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<modulelist><module>event</module><module>mpm_netware</module>
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync<module>mpmt_os2</module><module>worker</module></modulelist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>Minimum number of idle threads to handle request spikes.
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync Different MPMs deal with this directive
f72cbd6a549c34992fa79cce84600fe2b92b3299vboxsync differently.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p><module>worker</module> uses a default of <code>MinSpareThreads
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync 75</code> and deals with idle threads on a server-wide basis. If
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync there aren't enough idle threads in the server then child
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync processes are created until the number of idle threads is greater
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <code>MinSpareThreads 10</code> and, since it is a single-process
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync MPM, tracks this on a server-wide bases.</p>
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync <module>mpmt_os2</module> the default value is <code>5</code>.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<seealso><directive module="mpm_common">MaxSpareThreads</directive></seealso>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<seealso><directive module="mpm_common">StartServers</directive></seealso>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<seealso><directive module="prefork">MinSpareServers</directive></seealso>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<description>Location of the file used to store coordination data for
bff1915a855c5b71d76f6391549eadda348e33b0vboxsyncthe child processes</description>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<syntax>ScoreBoardFile <var>file-path</var></syntax>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<default>ScoreBoardFile logs/apache_status</default>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<contextlist><context>server config</context></contextlist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<modulelist><module>event</module><module>mpm_winnt</module>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<module>prefork</module><module>worker</module></modulelist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>Apache HTTP Server uses a scoreboard to communicate between its parent
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync and child processes. Some architectures require a file to facilitate
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync this communication. If the file is left unspecified, Apache httpd first
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync attempts to create the scoreboard entirely in memory (using anonymous
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync shared memory) and, failing that, will attempt to create the file on
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync disk (using file-based shared memory). Specifying this directive causes
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync Apache httpd to always create the file on the disk.</p>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync <p>File-based shared memory is useful for third-party applications
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync that require direct access to the scoreboard.</p>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync <p>If you use a <directive>ScoreBoardFile</directive> then
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync you may see improved speed by placing it on a RAM disk. But be
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync careful that you heed the same warnings about log file placement
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync and <a href="/misc/security_tips.html">security</a>.</p>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync<seealso><a href="/stopping.html">Stopping and Restarting
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync</directivesynopsis>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync<directivesynopsis>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync<contextlist><context>server config</context></contextlist>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync<modulelist><module>event</module><module>mpm_netware</module>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync<module>mpm_winnt</module><module>mpmt_os2</module><module>prefork</module>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync <p>The server will set the TCP receive buffer size to the number of
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync bytes specified.</p>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync <p>If set to the value of <code>0</code>, the server will use the
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync OS default.</p>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync</directivesynopsis>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync<directivesynopsis>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync<contextlist><context>server config</context></contextlist>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync<modulelist><module>event</module><module>mpm_netware</module>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync<module>mpm_winnt</module><module>mpmt_os2</module><module>prefork</module>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync <p>Sets the server's TCP send buffer size to the number of bytes
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync specified. It is often useful to set this past the OS's standard
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync default value on high speed, high latency conections
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync (<em>i.e.</em>, 100ms or so, such as transcontinental fast pipes).</p>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync <p>If set to the value of <code>0</code>, the server will use the
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync default value provided by your OS.</p>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync <p>Further configuration of your operating system may be required to elicit
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync better performance on high speed, high latency connections.</p>
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync <note> <p> On some operating systems, changes in TCP behavior resulting
ef811bab708f967b28bcdb7897e82b5e101eb226vboxsync from a larger <directive>SendBufferSize</directive> may not be seen unless
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <directive module="core">EnableSendfile</directive> is set to OFF. This
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync interaction applies only to static files.</p> </note>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<directivesynopsis>
66ce29e79816b3397896b0a0b273a3a61e4ceb74vboxsync<description>Upper limit on configurable number of processes</description>
432d08d68b9683d01880890d475a4cadd84b69cevboxsync<contextlist><context>server config</context></contextlist>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<modulelist><module>event</module><module>prefork</module>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>For the <module>prefork</module> MPM, this directive sets the
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync maximum configured value for <directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync module="mpm_common">MaxClients</directive> for the lifetime of the
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync Apache httpd process. For the <module>worker</module> MPM, this directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync in combination with <directive
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync the maximum configured value for <directive
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync module="mpm_common">MaxClients</directive> for the lifetime of the
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync Apache httpd process. Any attempts to change this directive during a
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync restart will be ignored, but <directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync module="mpm_common">MaxClients</directive> can be modified during
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync a restart.</p>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>Special care must be taken when using this directive. If
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <directive>ServerLimit</directive> is set to a value much higher
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync than necessary, extra, unused shared memory will be allocated. If
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync both <directive>ServerLimit</directive> and <directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync module="mpm_common">MaxClients</directive> are set to values
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync higher than the system can handle, Apache httpd may not start or the
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync system may become unstable.</p>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>With the <module>prefork</module> MPM, use this directive only
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync if you need to set <directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync module="mpm_common">MaxClients</directive> higher than 256 (default).
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync Do not set the value of this directive any higher than what you
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync might want to set <directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>With <module>worker</module>, use this directive only
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync if your <directive module="mpm_common">MaxClients</directive> and
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <directive module="mpm_common">ThreadsPerChild</directive>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync settings require more than 16 server processes (default). Do not set
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync the value of this directive any higher than the number of server
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync processes required by what you may want for <directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync module="mpm_common">MaxClients </directive> and <directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync module="mpm_common">ThreadsPerChild</directive>.</p>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>There is a hard limit of <code>ServerLimit 20000</code> compiled
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync into the server (for the <module>prefork</module> MPM 200000). This is
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync intended to avoid nasty effects caused by typos. To increase it
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync even further past this limit, you will need to modify the value of
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync MAX_SERVER_LIMIT in the mpm source file and rebuild the server.</p>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<seealso><a href="/stopping.html">Stopping and Restarting Apache HTTP Server</a></seealso>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync</directivesynopsis>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<directivesynopsis>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<description>Number of child server processes created at startup</description>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<contextlist><context>server config</context></contextlist>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<modulelist><module>event</module><module>mpmt_os2</module>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</modulelist>
b83e22f09e7f7a13f0c3c85a38392c5190731777vboxsync <p>The <directive>StartServers</directive> directive sets the
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync number of child server processes created on startup. As the number
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync of processes is dynamically controlled depending on the load, (see
aa0632eb844172ced4bef7b3afdbb216c8462fb2vboxsync <directive module="mpm_common">MinSpareThreads</directive>,
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <directive module="mpm_common">MaxSpareThreads</directive>,
66ce29e79816b3397896b0a0b273a3a61e4ceb74vboxsync <directive module="prefork">MinSpareServers</directive>, <directive
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync there is usually little reason to adjust this parameter.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>The default value differs from MPM to MPM. <module>worker</module>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync defaults to <code>StartServers 3</code>; <module>prefork</module>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync defaults to <code>5</code>; <module>mpmt_os2</module> defaults to
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync</directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<directivesynopsis>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync<description>Number of threads created on startup</description>
b9f5a22c6e86f7e09242c7483d8a67bd72f13a79vboxsync<contextlist><context>server config</context></contextlist>
b9f5a22c6e86f7e09242c7483d8a67bd72f13a79vboxsync<modulelist><module>mpm_netware</module></modulelist>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <p>Number of threads created on startup. As the
57958eb1223628d507daf47ed31ea25c4e8c6da9vboxsync number of threads is dynamically controlled depending on the
57958eb1223628d507daf47ed31ea25c4e8c6da9vboxsync <directive module="mpm_common">MinSpareThreads</directive>,
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <directive module="mpm_common">MaxSpareThreads</directive>,
57b49c1557a310ee615bc0ee79dd2a2e92319a1bvboxsync <directive module="prefork">MinSpareServers</directive>, <directive
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync there is usually little reason to adjust this
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync parameter.</p>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <code>StartThreads 50</code> and, since there is only a single
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync process, this is the total number of threads created at startup to
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync serve requests.</p>
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync</directivesynopsis>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<directivesynopsis>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<description>Sets the upper limit on the configurable number of threads
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsyncper child process</description>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<contextlist><context>server config</context></contextlist>
66ce29e79816b3397896b0a0b273a3a61e4ceb74vboxsync<modulelist><module>event</module><module>mpm_winnt</module>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<compatibility>Available for <module>mpm_winnt</module> in Apache HTTP Server 2.0.41
83dc9ca94cd3c31dabc33a35b945de124d43aaeavboxsyncand later</compatibility>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>This directive sets the maximum configured value for <directive
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync module="mpm_common">ThreadsPerChild</directive> for the lifetime
ee500238ee905283df7fc73c4ab22fce70e1da62vboxsync of the Apache httpd process. Any attempts to change this directive
ee500238ee905283df7fc73c4ab22fce70e1da62vboxsync during a restart will be ignored, but <directive
27ff3359094d10df126ef7c1009920d3a94d5bb7vboxsync module="mpm_common">ThreadsPerChild</directive> can be modified
27ff3359094d10df126ef7c1009920d3a94d5bb7vboxsync during a restart up to the value of this directive.</p>
66ce29e79816b3397896b0a0b273a3a61e4ceb74vboxsync <p>Special care must be taken when using this directive. If
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <directive>ThreadLimit</directive> is set to a value much higher
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync than <directive module="mpm_common">ThreadsPerChild</directive>,
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync extra unused shared memory will be allocated. If both
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync module="mpm_common">ThreadsPerChild</directive> are set to values
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync higher than the system can handle, Apache httpd may not start or the
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync system may become unstable. Do not set the value of this directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync any higher than your greatest predicted setting of <directive
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync module="mpm_common">ThreadsPerChild</directive> for the
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync current run of Apache httpd.</p>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>The default value for <directive>ThreadLimit</directive> is
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <code>1920</code> when used with <module>mpm_winnt</module> and
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>There is a hard limit of <code>ThreadLimit 20000</code> (or
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync <code>ThreadLimit 15000</code> with <module>mpm_winnt</module>)
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync compiled into the server. This is intended to avoid nasty effects
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync caused by typos. To increase it even further past this limit, you
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync will need to modify the value of MAX_THREAD_LIMIT in the mpm
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync source file and rebuild the server.</p>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync</directivesynopsis>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<directivesynopsis>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<description>Number of threads created by each child process</description>
83dc9ca94cd3c31dabc33a35b945de124d43aaeavboxsync<contextlist><context>server config</context></contextlist>
83dc9ca94cd3c31dabc33a35b945de124d43aaeavboxsync<modulelist><module>event</module><module>mpm_winnt</module>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>This directive sets the number of threads created by each
bff1915a855c5b71d76f6391549eadda348e33b0vboxsync child process. The child creates these threads at startup and
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync never creates more. If using an MPM like <module>mpm_winnt</module>,
57b49c1557a310ee615bc0ee79dd2a2e92319a1bvboxsync where there is only one child process, this number should be high
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync enough to handle the entire load of the server. If using an MPM
75e5dc3f6e81d0f296913553c86a632e06f76f8dvboxsync like <module>worker</module>, where there are multiple child processes,
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync the <em>total</em> number of threads should be high enough to handle
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync the common load on the server.</p>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>The default value for <directive>ThreadsPerChild</directive> is
aa0632eb844172ced4bef7b3afdbb216c8462fb2vboxsync <code>64</code> when used with <module>mpm_winnt</module> and
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync</directivesynopsis>
66ce29e79816b3397896b0a0b273a3a61e4ceb74vboxsync<directivesynopsis>
66ce29e79816b3397896b0a0b273a3a61e4ceb74vboxsync<description>The size in bytes of the stack used by threads handling
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsyncclient connections</description>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<default>65536 on NetWare; varies on other operating systems</default>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<contextlist><context>server config</context></contextlist>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<modulelist><module>event</module><module>mpm_netware</module>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<module>mpmt_os2</module><module>mpm_winnt</module><module>worker</module>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync</modulelist>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync<compatibility>Available in Apache HTTP Server 2.1 and later</compatibility>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <p>The <directive>ThreadStackSize</directive> directive sets the
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync size of the stack (for autodata) of threads which handle client
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync connections and call modules to help process those connections.
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync In most cases the operating system default for stack size is
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync reasonable, but there are some conditions where it may need to be
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync adjusted:</p>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <li>On platforms with a relatively small default thread stack size
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync (e.g., HP-UX), Apache httpd may crash when using some third-party modules
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync which use a relatively large amount of autodata storage. Those
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync same modules may have worked fine on other platforms where the
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync default thread stack size is larger. This type of crash is
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync resolved by setting <directive>ThreadStackSize</directive> to a
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync value higher than the operating system default. This type of
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync adjustment is necessary only if the provider of the third-party
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync module specifies that it is required, or if diagnosis of an Apache httpd
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync crash indicates that the thread stack size was too small.</li>
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync <li>On platforms where the default thread stack size is
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync significantly larger than necessary for the web server
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync configuration, a higher number of threads per child process
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync will be achievable if <directive>ThreadStackSize</directive> is
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync set to a value lower than the operating system default. This type
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync of adjustment should only be made in a test environment which allows
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync the full set of web server processing can be exercised, as there
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync may be infrequent requests which require more stack to process.
27018c8fbf977d7c4f67758c674736ff1c78804fvboxsync The minimum required stack size strongly depends on the modules
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync used, but any change in the web server configuration can invalidate
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync the current <directive>ThreadStackSize</directive> setting.</li>
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync <li>On Linux, this directive can only be used to increase the default
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync stack size, as the underlying system call uses the value as a
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync <em>minimum</em> stack size. The (often large) soft limit for
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync <code>ulimit -s</code> (8MB if unlimited) is used as the default stack
b3df226cc4728cfa969fd4fa30a86ee2fde4d4b1vboxsync <note>It is recommended to not reduce <directive>ThreadStackSize</directive>
b3df226cc4728cfa969fd4fa30a86ee2fde4d4b1vboxsync unless a high number of threads per child process is needed. On some
b3df226cc4728cfa969fd4fa30a86ee2fde4d4b1vboxsync platforms (including Linux), a setting of 128000 is already too low and
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync causes crashes with some common modules.</note>
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync</directivesynopsis>
fb1975a6972d89de9e515bed0248db93f04ec9d8vboxsync</modulesynopsis>