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FastCGI?><html><head><title>FastCGI (CGI Programming with Perl)</title><link href="../style/style1.css" type="text/css" rel="stylesheet" /><meta name="DC.Creator" content="Scott Guelich, Gunther Birznieks and Shishir Gundavaram" /><meta scheme="MIME" content="text/xml" name="DC.Format" /><meta content="en-US" name="DC.Language" /><meta content="O'Reilly & Associates, Inc." name="DC.Publisher" /><meta scheme="ISBN" name="DC.Source" content="1565924193L" /><meta name="DC.Subject.Keyword" content="stuff" /><meta name="DC.Title" content="CGI Programming with Perl" /><meta content="Text.Monograph" name="DC.Type" /></head><body bgcolor="#ffffff"><img src="gifs/smbanner.gif" alt="Book Home" usemap="#banner-map" border="0" /><map name="banner-map"><area alt="CGI Programming with Perl" href="index.htm" coords="0,0,466,65" shape="rect" /><area alt="Search this book" href="jobjects/fsearch.htm" coords="467,0,514,18" shape="rect" /></map><div class="navbar"><table border="0" width="515"><tr><td width="172" valign="top" align="left"><a href="ch17_01.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td width="171" valign="top" align="center"><a href="index.htm">CGI Programming with Perl</a></td><td width="172" valign="top" align="right"><a href="ch17_03.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><hr align="left" width="515" /><h2 class="sect1">17.2. FastCGI</h2><p>FastCGI is a web <a name="INDEX-3264" /> <a name="INDEX-3265" /><a name="INDEX-3266" /><a name="INDEX-3267" />serverextension that allows you to convert CGI programs into persistent,long-lived server-like applications. The web server spawns a FastCGIprocess for each specified CGI application at startup, and theseprocesses respond to requests, until they are explicitly terminated.If you expect a certain application to be used more than others, youcan also ask FastCGI to spawn multiple processes to handle concurrentrequests.</p><p>There are several advantages to this approach. A typical Perl CGIapplication has startup overhead for each request that includes theprocess of spawning a process and interpreting the code. And, if thecode has a lengthy initialization process, that simply adds to theoverhead. A typical FastCGI application does not suffer from any ofthese problems. There is no extra spawning for each request, and allthe initialization is done at startup. Since these applications arelong-lived, they allow you to store data between requests, which isalso an advantage.</p><p><a href="ch17_02.htm#ch17-89196">Example 17-1</a> shows what a typical CGI script lookslike.</p><a name="ch17-89196" /><div class="example"><h4 class="objtitle">Example 17-1. fast_count.cgi </h4><blockquote><pre class="code">#!/usr/bin/perl -wTuse strict;use vars qw( $count );use FCGI;local $count = 0;while ( FCGI::accept >= 0 ) { $count++; print "Content-type: text/plain\n\n"; print "You are request number $count. Have a good day!\n";}</pre></blockquote></div><p>Other than a few extra details, this is not much different than aregular CGI program. Since this is initialized only once, the valueof <tt class="literal">$count</tt> (a global variable) will be zero atstartup and will be persistent for all subsequent requests. If theweb server receives a request for this FastCGI application, it passesit on and the FCGI::accept accepts the request and returns aresponse, which executes the body of the <em class="emphasis">while</em>loop. In this case, you will notice that the value of<tt class="literal">$count</tt> will be incremented for each request.</p><p>If your CGI script uses CGI.pm, you can use CGI.pm's FastCGIinterface, CGI::Fast, instead. <a name="INDEX-3268" />CGI::Fast is included in the standardCGI.pm distribution. <a href="ch17_02.htm#ch17-83330">Example 17-2</a> shows how <a href="ch17_02.htm#ch17-89196">Example 17-1</a> looks with CGI::Fast.</p><a name="ch17-83330" /><div class="example"><h4 class="objtitle">Example 17-2. fast_count.cgi </h4><blockquote><pre class="code">#!/usr/bin/perl -wTuse strict;use vars qw( $count );use CGI::Fast;local $count = 0;while ( my $q = new CGI::Fast ) { $count++; print $q->header( "text/plain" ), "You are request number $count. Have a good day!\n";}</pre></blockquote></div><p>This works the same way. Everything before the creation of aCGI::Fast object is only executed once. Then the script waits untilit receives a request, which creates a new CGI::Fast object and runsthe body of the <em class="emphasis">while</em> loop.</p><p>Now that you've seen how FastCGI works, let's see how toinstall it. FastCGI works with a wide variety of web servers, butwe'll walk through the setup for Apache.</p><a name="ch17-11-fm2xml" /><div class="sect2"><h3 class="sect2">17.2.1. Installing FastCGI</h3><p>Early versions of<a name="INDEX-3269" /><a name="INDEX-3270" />FastCGIrequired a modified version of Perl to work its magic. Fortunately,this is no longer the case. However, FastCGI does require a change toyour web server. The FastCGI distribution includes modules for yourweb server as well as the Perl module, FCGI (which is also availableon CPAN). You can obtain it from <a href="http://www.fastcgi.com/">http://www.fastcgi.com/</a>, the home of theFastCGI open source project. Note this is separate from <a href="http://www.fastcgi.org/">http://www.fastcgi.org/</a>, which offerscommercial solutions built upon FastCGI. In this case the<em class="emphasis">.org</em> and <em class="emphasis">.com</em> web sites arethe reverse of what you might expect.</p><p>Here are the instructions for installing FastCGI with<a name="INDEX-3271" />Apache. If you're usinga version of Apache greater than 1.3, you can simply runApache's <em class="emphasis">configure</em> in the followingmanner:</p><blockquote><pre class="code">configure --add-module=/usr/local/src/apache-fastcgi/src/mod_fastcgi.c</pre></blockquote><p>Then, you need to determine where you will place your FastCGIapplications. We let Apache know the location by adding the followingdirectives in <em class="filename">httpd.conf</em>(<tt class="literal">Location</tt> goes in<em class="emphasis">access.conf</em>, and <tt class="literal">Alias</tt> in<em class="emphasis">srm.conf</em> if used):</p><blockquote><pre class="code"><Location /fcgi>SetHandler fastcgi-script</Location>Alias /fcgi/ /usr/local/apache/fcgi/</pre></blockquote><p>For each FastCGI application that you want to start, you need to makean entry like the following:</p><blockquote><pre class="code">AppClass /usr/local/apache/fcgi/fast_count.cgi</pre></blockquote><p>Now, when you start your Apache server, you should see a<em class="emphasis">fcgi_count</em> process in your system'sprocess table. And you can access it by simply pointing your browserat:</p><blockquote class="simplelist"><p><em class="emphasis">http://localhost/fcgi/fast_count.cgi</em></p></blockquote><p>Go ahead and convert one of your applications to FastCGI.You'll see a major speed improvement. Before you do that,however, a few things to note. You should fix all memory leaks withinyour FastCGI programs, or else it could drastically effect yoursystem resources. So, make sure to begin your scripts this way:</p><blockquote><pre class="code">#!/usr/bin/perl -wTuse strict;</pre></blockquote><p>to check for warnings and to restrict variable scope.</p><p>Also, you should think about collapsing the functionality from yourvarious CGI applications. Since CGI applications incur significantoverhead for each request, it is a common practice to split thefunctionality into several little applications to reduce theoverhead. But, with FastCGI, that is no longer a concern.</p><p>FastCGI offers other functionality as well, including the ability forthe local web server to run FastCGI programs on remote machines.It's beyond the scope of this chapter to go into detail aboutthat topic, but you can find more information in the FastCGIdocumentation.</p><p>The technology we are about to look at offers high speed improvementsover conventional CGI applications, much like FastCGI, but does so inan entirely <a name="INDEX-3272" /> <a name="INDEX-3273" /> <a name="INDEX-3274" /> <a name="INDEX-3275" />different manner.</p></div><hr align="left" width="515" /><div class="navbar"><table border="0" width="515"><tr><td width="172" valign="top" align="left"><a href="ch17_01.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td width="171" valign="top" align="center"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td width="172" valign="top" align="right"><a href="ch17_03.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td width="172" valign="top" align="left">17. Efficiency and Optimization</td><td width="171" valign="top" align="center"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td width="172" valign="top" align="right">17.3. mod_perl</td></tr></table></div><hr align="left" width="515" /><img src="../gifs/navbar.gif" alt="Library Navigation Links" usemap="#library-map" border="0" /><p><font size="-1"><a href="copyrght.htm">Copyright © 2001</a> O'Reilly & Associates. 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