Re: Re: [PHP3] How exactly does PHP work ?

Addressed to: richard@zend.com (Richard Lynch) php-general@lists.php.net ** Reply to note from richard@zend.com (Richard Lynch) Tue, 20 Jun 2000 19:09:02 -0500 > > In article <3949EA44.34C34C37@t-edge.com>, mandar@t-edge.com (Mandar > Deshmukh) wrote: > > > I wanted to know, on each new user accessing a php page, what is > > created on the server? : > > 1) a object, > > 2) a thread, > > 3) a process > > Learning something about this will give me a clearer picture of php > > Using PHP as a Module, I think maybe just a thread, if that much, is > created. I guess it has to create some sort of discrete thing, since > one PHP incarnation on a server is independent of another... > I don't know about other servers, but with Apache, if you have spare processes waiting for connections (the normal situation) _nothing_ is created. Apache spawns some number (StartServers) of servers, and adjusts thier number (MinSpareServers, MaxSpareServers) to have pre-spawned processes ready to handle requests. In a module based PHP install, each of these processes includes PHP code, and is ready to execute your PHP program. The root Apache process is listening on port 80 and maybe 443 (Listen, VirtualHost) all the time. When a request comes in it is dispatced to one of the waiting servers. If there are a large number of processes actively doing work Apache creates more processes (up to MaxSpareServers) to keep some idle server processes in memory, ready to handle a request. This is why you see one Apache process owned by root, and many owned by nobody. (User, Group) For more info, read up on the Apache configuration directives listed above ()... PS. In an earlier message I mentioned that the root apache process was needed for re-reading the config files, now that I've thought about it more, a root process is also needed to be able to listen to ports less than 1024, on a UNIX based machine. So the main reason for the root owned process is to listen on the privleged (<1024) port and dispatch the request to a waiting slave. Rick Widmer Internet Marketing Specialists www.developersdesk.com