On Sep 29, 2005, at 8:03 AM, Simon Willison wrote:
That's more a limitation of mod_python than of Django itself. I imagine that FastCGI and SCGI avoid this issue almost entirely - the modules themselves are much smaller so it's less wasteful to use them to serve static files as well as Django stuff.
More specifically: mod_python uses in-process Python interpreters, hence Python, Django, psycopg, etc. are all going to be loaded into the Apache child's memory space. FastCGI/SCGI use external Python processes which communicate over sockets with Apache. Thus the waste when using FastCGI/SCGI is limited to libraries that are pretty much a glorified read() from one socket and write() to another.
However, even with FCGI/SCGI it's still a performance hit to serve both static and dynamic files from the same server. Your goals when tuning a web server for dynamic content are pretty much the opposite as those when tuning a server for static content.
To pick one example: in a dynamic serving situation, KeepAlive is your friend; you want to keep the number of open connections to a minimum since each open connection adds another FCGI socket, another database connection, etc. It's preferable to have "stale" KeepAlive sessions over so many connections that you overwhelm your database or whatever. On the other hand, when you're serving lots of small media files KeepAlive is your enemy; you want to pump out as many files as you possibly can, and processes waiting to handle the next KeepAlive request are going to kill throughput.
Jacob
