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