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435 lines
13 KiB
HTML
435 lines
13 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<TITLE>Apache MPM mpmt_pthread</TITLE>
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</HEAD>
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<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
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<BODY
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#000080"
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ALINK="#FF0000"
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>
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<!--#include virtual="header.html" -->
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<H1 ALIGN="CENTER">Mulit-Processing Module mpmt_pthread</H1>
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<P>
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This Multi-Processing Module controls process and thread creation
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using the pthread interface.
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</P>
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<P><A
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HREF="module-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> MPM
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<BR>
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<A
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HREF="module-dict.html#SourceFile"
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REL="Help"
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><STRONG>Source File:</STRONG></A> mpmt_pthread.c
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<BR>
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<A
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HREF="module-dict.html#ModuleIdentifier"
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REL="Help"
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><STRONG>Module Identifier:</STRONG></A> mpm_mpmt_pthread_module
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</P>
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<H2>Summary</H2>
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<p>This Multi-Processing Module (MPM) is the default for most unix-like
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operating systems. It uses pthread system calls to create a hybrid
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multi-process multi-threaded server. Each process has a fixed number
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of threads. The server adjusts to handle load by increasing or
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decreasing the number of processes.</p>
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<H2>Directives</H2>
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<UL>
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<li><a href="#coredumpdirectory">CoreDumpDirectory</a></li>
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<li><a href="#pidfile">PidFile</a></li>
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<li><a href="#lockfile">LockFile</a></li>
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<li><a href="#maxclients">MaxClients</a></li>
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<li><a href="#maxrequestsperchild">MaxRequestsPerChild</a></li>
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<li><a href="#maxsparethreads">MaxSpareThreads</a></li>
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<li><a href="#minsparethreads">MinSpareThreads</a></li>
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<li><a href="#scoreboardfile">ScoreBoardFile</a></li>
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<li><a href="#startservers">StartServers</a></li>
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<li><a href="#threadsperchild">ThreadsPerChild</a></li>
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</UL>
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<HR>
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<H2><A NAME="coredumpdirectory">CoreDumpDirectory directive</A></H2>
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<!--%plaintext <?INDEX {\tt CoreDumpDirectory} directive> -->
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> CoreDumpDirectory <EM>directory</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> the same location as ServerRoot<BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> Base<BR>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<p>This controls the directory to which Apache attempts to switch
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before dumping core. The default is in the <A
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HREF="core.html#serverroot">ServerRoot</A> directory, however since
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this should not be writable by the user the server runs as, core dumps
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won't normally get written. If you want a core dump for debugging,
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you can use this directive to place it in a different location.<P><HR>
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<H2><A NAME="pidfile">PidFile directive</A></H2>
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<!--%plaintext <?INDEX {\tt PidFile} directive> -->
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> PidFile <EM>filename</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> <CODE>PidFile logs/httpd.pid</CODE><BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> Base<BR>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<p>The PidFile directive sets the file to which the server records the
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process id of the daemon. If the filename does not begin with a slash
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(/) then it is assumed to be relative to the <A
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HREF="core.html#serverroot">ServerRoot</A>.</p>
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<p>It is often useful to be able to send the server a signal, so that
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it closes and then reopens its <A
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HREF="core.html#errorlog">ErrorLog</A> and TransferLog, and re-reads
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its configuration files. This is done by sending a SIGHUP (kill -1)
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signal to the process id listed in the PidFile.</p>
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<p>The PidFile is subject to the same warnings about log file placement and
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<A HREF="../misc/security_tips.html#serverroot">security</A>.</p>
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<P><HR>
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<H2><A NAME="lockfile">LockFile directive</A></H2>
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> LockFile <EM>filename</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> <CODE>LockFile logs/accept.lock</CODE><BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> Base<BR>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<p>The LockFile directive sets the path to the lockfile used when
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Apache is compiled with either USE_FCNTL_SERIALIZED_ACCEPT or
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USE_FLOCK_SERIALIZED_ACCEPT. This directive should normally be
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left at its default value. The main reason for changing it is if
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the <CODE>logs</CODE> directory is NFS mounted, since <STRONG>the lockfile
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must be stored on a local disk</STRONG>. The PID of the main
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server process is automatically appended to the filename. <P>
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<p><STRONG>SECURITY:</STRONG> It is best to avoid putting this file in a
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world writable directory such as <CODE>/var/tmp</CODE> because someone
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could create a denial of service attack and prevent the server from
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starting by creating a lockfile with the same name as the one the
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server will try to create.</p>
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<hr>
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<H2><A NAME="maxclients">MaxClients directive</A></H2>
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<!--%plaintext <?INDEX {\tt MaxClients} directive> -->
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> MaxClients <EM>number</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> <CODE>MaxClients 8</code> (with threads)
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<code>MaxClients 256</code> (no threads)<BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> core<BR>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<P>The MaxClients directive sets the limit on the number of child
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processes that will be created to serve requests. When the server is
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built without threading, no more than this number of clients can be
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served simultaneously. To configure more than 256 clients, you must
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edit the <code>HARD_SERVER_LIMIT</code> entry in
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<code>mpm_default.h</code> and recompile.
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<P>Any connection attempts over the MaxClients limit will normally
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be queued, up to a number based on the <A HREF="#listenbacklog">
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ListenBacklog</A> directive. Once a child process is freed at the
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end of a different request, the connection will then be serviced.</p>
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<p>When the server is compiled with threading, then the maximum number
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of simultaneous requests that can be served is obtained from the value
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of this directive multiplied by <a
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href="#threadsperchild">ThreadsPerChild</a>.</p>
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<HR>
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<H2><A NAME="maxrequestsperchild">MaxRequestsPerChild directive</A></H2>
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<!--%plaintext <?INDEX {\tt MaxRequestsPerChild} directive> -->
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> MaxRequestsPerChild <EM>number</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> <CODE>MaxRequestsPerChild 10000</CODE><BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> core<BR>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<p>The MaxRequestsPerChild directive sets the limit on the number of requests
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that an individual child server process will handle. After MaxRequestsPerChild
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requests, the child process will die. If MaxRequestsPerChild is 0, then
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the process will never expire.<P>
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Setting MaxRequestsPerChild to a non-zero limit has two beneficial effects:
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<UL>
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<LI>it limits the amount of memory that process can consume by (accidental)
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memory leakage;
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<LI> by giving processes a finite lifetime, it helps reduce the
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number of processes when the server load reduces.
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</UL>
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<P><STRONG>NOTE:</STRONG> For <EM>KeepAlive</EM> requests, only the first
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request is counted towards this limit. In effect, it changes the
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behavior to limit the number of <EM>connections</EM> per child.
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<P><HR>
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<H2><A NAME="maxsparethreads">MaxSpareThreads directive</A></H2>
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<!--%plaintext <?INDEX {\tt MaxSpareServers} directive> -->
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> MaxSpareThreads <EM>number</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> <CODE>MaxSpareThreads ??</CODE><BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> core<BR>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<P>Content needed here!</p>
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<p>See also <A HREF="#minsparethreads">MinSpareThreads</A> and
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<A HREF="#startservers">StartServers</A>.
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<P><HR>
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<H2><A NAME="minsparethreads">MinSpareThreads directive</A></H2>
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<!--%plaintext <?INDEX {\tt MinSpareServers} directive> -->
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> MinSpareServers <EM>number</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> <CODE>MinSpareServers ???</CODE><BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> core<BR>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<p><strong>fix me</strong></p>
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<p>The MinSpareServers directive sets the desired minimum number of <EM>idle</EM>
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child server processes. An idle process is one which is not handling
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a request. If there are fewer than MinSpareServers idle, then the parent
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process creates new children at a maximum rate of 1 per second.<P>
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Tuning of this parameter should only be necessary on very busy sites.
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Setting this parameter to a large number is almost always a bad idea.<P>
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This directive has no effect on Microsoft Windows.
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<P>
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See also <A HREF="#maxsparethreads">MaxSpareThreads</A> and
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<A HREF="#startservers">StartServers</A>.<P><HR>
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<H2><A NAME="scoreboardfile">ScoreBoardFile directive</A></H2>
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<!--%plaintext <?INDEX {\tt ScoreBoardFile} directive> -->
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> ScoreBoardFile <EM>filename</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> <CODE>ScoreBoardFile logs/apache_status</CODE>
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<BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> Base<BR>
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<A
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HREF="directive-dict.html#Compatibility"
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REL="Help"
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>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<p>The ScoreBoardFile directive is required on some architectures to place
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a file that the server will use to communicate between its children and
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the parent. The easiest way to find out if your architecture requires
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a scoreboard file is to run Apache and see if it creates the file named
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by the directive. If your architecture requires it then you must ensure
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that this file is not used at the same time by more than one invocation
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of Apache.</p>
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<p>If you have to use a ScoreBoardFile then you may see improved speed by
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placing it on a RAM disk. But be careful that you heed the same warnings
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about log file placement and
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<A HREF="../misc/security_tips.html">security</A>.</p>
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<p><STRONG>See Also</STRONG>:
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<A HREF="../stopping.html">Stopping and Restarting Apache</A></P>
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<P><HR>
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<H2><A NAME="startservers">StartServers directive</A></H2>
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<!--%plaintext <?INDEX {\tt StartServers} directive> -->
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> StartServers <EM>number</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> <CODE>StartServers 5</CODE><BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> core<BR>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<p>The StartServers directive sets the number of child server processes created
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on startup. As the number of processes is dynamically controlled depending
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on the load, there is usually little reason to adjust this parameter.</P>
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<P>See also <A HREF="#minsparethreads">MinSpareThreads</A> and
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<A HREF="#maxsparethreads">MaxSpareThreads</A>.<P><HR>
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<H2><A NAME="threadsperchild">ThreadsPerChild</A></H2>
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<p><A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> ThreadsPerChild <EM>number</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> <CODE>ThreadsPerChild 50</CODE><BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> Base<BR>
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<A
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HREF="directive-dict.html#Module"
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REL="Help"
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><STRONG>Module:</STRONG></A> mpmt_pthread</p>
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<P>This directive sets the number of threads created by each child
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process.</p>
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<!--#include virtual="footer.html" -->
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</BODY>
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</HTML>
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