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<H1 ALIGN="CENTER">Module mod_mmap_static</H1>
<P>
Apache 1.3 and later. It provides mmap()ing of a statically configured list
of frequently requested but not changed files. It is not compiled into the
server by default. To use <CODE>mod_mmap_static</CODE> you have to enable
the following line in the server build <CODE>Configuration</CODE> file:
<PRE>
</PRE>
</P>
<H2>Summary</H2>
<P>
This is an <STRONG>experimental</STRONG> module and should be used with
care. It maps a list of statically configured files (via
<CODE>MMapFile</CODE> directives in the main server configuration) into
memory through the system call <CODE>mmap()</CODE>. Although this system
call is not available on every platform, most of the modern Unix derivates
provide it. At least those ones conforming to the POSIX.4 definition. The
size of the mapable files usually has to be less then 2GB. But this is no
real restriction for documents on a webserver.
</P>
<P>
This mmap()ing is done once at server start or restart, only. So whenever
one of the mapped files changes on the filesystem you <EM>have</EM> to
restart the server by at least sending it a HUP or USR1 signal. To
reiterate that point: if the files are modified <EM>in place</EM> without
restarting the server you may end up serving requests that are completely
bogus. You should update files by unlinking the old copy and putting a new
copy in place. Most tools such as <CODE>rdist</CODE> and <CODE>mv</CODE> do
this. The reason why this modules doesn't take care of changes to the files
is that this check would need an extra <CODE>stat()</CODE> every time which
is a waste and against the intend of I/O reduction.
</P>
<H2>Directives</H2>
<UL>
<LI><A HREF="#mmapfile">MMapFile</A>
</LI>
</UL>
<HR>
<H2><A NAME="mmapfile">MMapFile</A></H2>
<P>
<A
HREF="directive-dict.html#Syntax"
REL="Help"
><STRONG>Syntax:</STRONG></A> MMapFile <EM>filename ...</EM>
<BR>
<A
HREF="directive-dict.html#Default"
REL="Help"
><STRONG>Default:</STRONG></A> <EM>None</EM>
<BR>
<A
HREF="directive-dict.html#Context"
REL="Help"
><STRONG>Context:</STRONG></A> server-config
<BR>
<A
HREF="directive-dict.html#Override"
REL="Help"
><STRONG>Override:</STRONG></A> <EM>Not applicable</EM>
<BR>
<A
HREF="directive-dict.html#Status"
REL="Help"
><STRONG>Status:</STRONG></A> Experimental
<BR>
<A
HREF="directive-dict.html#Module"
REL="Help"
><STRONG>Module:</STRONG></A> mod_mmap_static
<BR>
<A
HREF="directive-dict.html#Compatibility"
REL="Help"
><STRONG>Compatibility:</STRONG></A> Only available in Apache 1.3 or later
<P>
The <CODE>MMapFile</CODE> directive maps one or more files (given as
whitespace separated arguments) into memory at server startup time. They
are automatically unmapped on a server shutdown. When the files have changed
on the filesystem at least a HUP or USR1 signal should be send to the server
to re-mmap them.
</P>
<P>
Be careful with the <EM>filename</EM> arguments: They have to literally
match the filesystem path Apache's URL-to-filename translation handlers
create. We cannot compare inodes or other stuff to match paths through
symbolic links etc. because that again would cost extra <CODE>stat()</CODE>
system calls which is not acceptable.
</P>
<P>
Notice: You cannot use this for speeding up CGI programs or other files
which are served by special content handlers. It can only be used for
regular files which are usually served by the Apache core content handler.
</P>
Example:
<PRE>
</PRE>
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