On Fri, 2008-09-05 at 18:49 +0900, Andrej van der Zee wrote: > Hi, > > > > > A CGI script is run by the code of a module, mod_perl, mod_php5, etc. > > In their register_hooks function they register their handler, which is > > a script interpreter basically. The handler callback is invoked in the > > same thread that did the rest of the request processing (URL parsing, > > authentication, fixups, etc).
I think there seems to be a confusion about terminology here: a CGI-script by definition runs in its own process, _not_ within the process address space of the webserver (hence the need for a defined "Common Gateway Interface" to pass request information to the external application. See http://en.wikipedia.org/wiki/Common_Gateway_Interface). Now, since the forking/spanwing is a rather time consuming operation there are embedded interpreters for most of the commons scripting languages (like perl/python etc.). Those often have a compatibility layer to run unmodified CGI code within the webservers address/process space (with sometimes strage side efects :-/). > However, I don't know if the handler > > callback (of mod_perl, mod_php5, etc), which can be seen as a sort of > > third-party black box, spawns new processes/threads in which they > > parse the script, compile, etc. I guess they do not spawn new > > threads/processes but you have to read their docs or their sources in > > order to be sure. If they do not spawn new threads/processes, then the > > CGI is executed in the same thread as fixups and the rest of the > > request processing. > > > > Thanks that makes sense. > > If understood correctly, this means that I can add my own module to > the chain of request processors that executes in the same thread as > the hook function in mod_php5/mod_perl that executes CGI scripts. For the embedded interpreters that's true. > Though, if the module's hook function spawns a new process/thread for > handling the CGI script is dependent on the module. CGIs are handled by mod_cgi. > Does anybody know if the hook functions of such modules usually > spawning a new thread/process? My guess is that at least for compiled > CGI application written in C/C++ a new process is forked in the hook > function. Iff those are real CGIs (applications) that's true. HTH Ralf Mattes > Cheers, > Andrej > >
