<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <title>6.3 CGI Handler</title> <META NAME="description" CONTENT="6.3 CGI Handler"> <META NAME="keywords" CONTENT="modpython"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <link rel="STYLESHEET" href="modpython.css"> <link rel="first" href="modpython.html"> <link rel="contents" href="contents.html" title="Contents"> <link rel="index" href="genindex.html" title="Index"> <LINK REL="previous" href="hand-psp.html"> <LINK REL="up" href="handlers.html"> <LINK REL="next" href="app-changes.html"> </head> <body> <DIV CLASS="navigation"> <table align="center" width="100%" cellpadding="0" cellspacing="2"> <tr> <td><A href="hand-psp.html"><img src="icons/previous.png" border="0" height="32" alt="Previous Page" width="32"></A></td> <td><A href="handlers.html"><img src="icons/up.png" border="0" height="32" alt="Up One Level" width="32"></A></td> <td><A href="app-changes.html"><img src="icons/next.png" border="0" height="32" alt="Next Page" width="32"></A></td> <td align="center" width="100%">Mod_python Manual</td> <td><A href="contents.html"><img src="icons/contents.png" border="0" height="32" alt="Contents" width="32"></A></td> <td><img src="icons/blank.png" border="0" height="32" alt="" width="32"></td> <td><A href="genindex.html"><img src="icons/index.png" border="0" height="32" alt="Index" width="32"></A></td> </tr></table> <b class="navlabel">Previous:</b> <a class="sectref" href="hand-psp.html">6.2 PSP Handler</A> <b class="navlabel">Up:</b> <a class="sectref" href="handlers.html">6. Standard Handlers</A> <b class="navlabel">Next:</b> <a class="sectref" href="app-changes.html">A. Changes from Previous</A> <br><hr> </DIV> <!--End of Navigation Panel--> <H1><A NAME="SECTION008300000000000000000"> </A> <BR> 6.3 CGI Handler </H1> <P> <a name="l2h-244"> </a> <P> CGI handler is a handler that emulates the CGI environment under mod_python. <P> Note that this is not a "<tt class="samp">true</tt>" CGI environment in that it is emulated at the Python level. <code>stdin</code> and <code>stdout</code> are provided by substituting <code>sys.stdin</code> and <code>sys.stdout</code>, and the environment is replaced by a dictionary. The implication is that any outside programs called from within this environment via <code>os.system</code>, etc. will not see the environment available to the Python program, nor will they be able to read/write from standard input/output with the results expected in a "<tt class="samp">true</tt>" CGI environment. <P> The handler is provided as a stepping stone for the migration of legacy code away from CGI. It is not recommended that you settle on using this handler as the preferred way to use mod_python for the long term. This is because the CGI environment was not intended for execution within threads (e.g. requires changing of current directory with is inherently not thread-safe, so to overcome this cgihandler maintains a thread lock which forces it to process one request at a time in a multi-threaded server) and therefore can only be implemented in a way that defeats many of the advantages of using mod_python in the first place. <P> To use it, simply add this to your <span class="file">.htaccess</span> file: <P> <dl><dd><pre class="verbatim"> SetHandler mod_python PythonHandler mod_python.cgihandler </pre></dl> <P> As of version 2.7, the cgihandler will properly reload even indirectly imported module. This is done by saving a list of loaded modules (sys.modules) prior to executing a CGI script, and then comparing it with a list of imported modules after the CGI script is done. Modules (except for whose whose __file__ attribute points to the standard Python library location) will be deleted from sys.modules thereby forcing Python to load them again next time the CGI script imports them. <P> If you do not want the above behavior, edit the <span class="file">cgihandler.py</span> file and comment out the code delimited by ###. <P> Tests show the cgihandler leaking some memory when processing a lot of file uploads. It is still not clear what causes this. The way to work around this is to set the Apache <code>MaxRequestsPerChild</code> to a non-zero value. <P> <DIV CLASS="navigation"> <p><hr> <table align="center" width="100%" cellpadding="0" cellspacing="2"> <tr> <td><A href="hand-psp.html"><img src="icons/previous.png" border="0" height="32" alt="Previous Page" width="32"></A></td> <td><A href="handlers.html"><img src="icons/up.png" border="0" height="32" alt="Up One Level" width="32"></A></td> <td><A href="app-changes.html"><img src="icons/next.png" border="0" height="32" alt="Next Page" width="32"></A></td> <td align="center" width="100%">Mod_python Manual</td> <td><A href="contents.html"><img src="icons/contents.png" border="0" height="32" alt="Contents" width="32"></A></td> <td><img src="icons/blank.png" border="0" height="32" alt="" width="32"></td> <td><A href="genindex.html"><img src="icons/index.png" border="0" height="32" alt="Index" width="32"></A></td> </tr></table> <b class="navlabel">Previous:</b> <a class="sectref" href="hand-psp.html">6.2 PSP Handler</A> <b class="navlabel">Up:</b> <a class="sectref" href="handlers.html">6. Standard Handlers</A> <b class="navlabel">Next:</b> <a class="sectref" href="app-changes.html">A. Changes from Previous</A> <hr> <span class="release-info">Release 3.1.0a, documentation updated on August 26, 2003.</span> </DIV> <!--End of Navigation Panel--> </BODY> </HTML>
