On Oct 22, 9:49 am, "Jon Rosebaugh"
<chai...@public.gmane.org> wrote:

FWIW, I also never quite understood the basis for getting the equivalent of Apache mod_wsgi working on nginx because how nginx works somewhat limits its overall usefulness. All the same, I haven't objected to the person trying and using code from Apache mod_wsgi in the process.

The big difference between how Apache works and how nginx works (correct me if I am wrong) is that nginx uses an asynchronous event driven model, running with a fixed number of worker processes. This makes it somewhat hard to extend it with embedded modules that are able to block, as when the application supported by the module blocks, the whole process blocks. Although with Apache prefork MPM any one child process can also block completely, Apache can dynamically create additional child processes to cope with a spike in demand or when existing child processes are busy.

In nginx, my understanding is that it isn't able to create additional worker processes like Apache is able to, which would be somewhat limiting. Also understand that nginx isn't internally thread safe at this point, so trying to use Python level threads to allow a blocking mode of operating to work on top of nginx asynchronous model seems also to be problematic.

Thus, in order to support still being able to handle other requests such as those for static files, or proxying requests through to another HTTP server or FASTCGI process, my understanding is that they originally expected that the nginx with embedded WSGI support would itself be run as a backend server to which you would proxy from a front end nginx instance which would do all the other work. In other words, WSGI in nginx is merely attempting to use the nginx web server stack in the belief that it would provide a better performing WSGI server, but not really provide the services of a general purpose web server at the same time.

In this respect, it isn't really any different to proxying to paste.httpserver or using a nginx FASTCGI solution.

So Jon, we may not see eye to eye on how Apache mod_wsgi is implemented or when it would be appropriate to use it, but on nginx mod_wsgi, we would at least appear to have the same view. ;-)

Graham