On Mon, Feb 9, 2009 at 8:26 AM, Graham Dumpleton <[email protected]> wrote: > > In response to some claims about mod_wsgi embedded mode being worse > than daemon mode and with it being said to be no better than > mod_python, I have updated: > > http://code.google.com/p/modwsgi/wiki/PerformanceEstimates > > with a few comments about how it is important not to use default MPM > settings for mod_wsgi and mod_python if using embedded mode. > > I intend to blog about this some more, but first have a question which > someone knowledgeable about PHP can perhaps help me with. > > In PHP, it preloads all its extension modules in the Apache parent > process. That is, they have been loaded even before Apache forks off > the child processes which handle requests. As a result, creation of > new child processes capable of handling PHP requests is very quick > with neglible overhead. > > In contrast, for mod_python/mod_wsgi, only the Python interpreter is > initialised in the Apache parent process. Any extension modules are > only loaded in the child process when an application runs in response > to handling a request. > > This lazy loading with Python means that there can be significant > delayed startup cost which occurs only in the child processes and > which is incurred in every child process created. Part of the comments > in that updated wiki page highlight how the default MPM settings in > Apache are actually probably really bad in respect of this, > specifically where fat Python web applications are use. > > As to my question, what I want to know is if for PHP if all extension > modules are always preloaded and thus user code has no ability to load > any additional modules itself. In other words, are PHP users at the > mercy of the administrator as far as what extension modules are > available, and if they want something else they are stuffed? Or, can a > user somehow install an extension module somewhere himself and say > that it should be loaded by his application, much like Python's import > system works?
When it comes to C extensions, PHP does not have anything that will allow you to dynamically load extensions at runtime. So yes, essentially you are stuck with whatever PHP configuration that your virtual hosting provides if you are using Apache SAPI. If you are using CGI it might be possible via wrapper scripts to run PHP with a different php.ini and load your own C-extensions. However a lot of virtual hosting providers do not allow this for security reasons. There is also the fact that you must compile your extensions against *the same* libraries that your server's PHP and Apache are compiled against. I have to agree that the default MPM settings provided with Apache out of the box can hurt mod_wsgi performance.Comparing an out of the box install of Apache+mod_wsgi against PHP on a virtual hosting provider is not a fair comparison. Virtual hosting providers already have pre-tuned Apache configurations that are geared towards PHP application performance. By tweaking our server's MPM configuration I was able to achieve equal if not better performance with mod_wsgi. Although YMMV as different applications will have different needs. -- Best Regards, Nimrod A. Abing W http://arsenic.ph/ W http://preownedcar.com/ W http://preownedbike.com/ W http://abing.gotdns.com/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "modwsgi" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/modwsgi?hl=en -~----------~----~----~----~------~----~------~--~---
