On Fri, Apr 29, 2005 at 11:53:30AM -0500, Ian Bicking wrote:
I can imagine a good setup for hosts being one based on forking per-user processes, which is adaptive primarily to scale down -- e.g., a largely dorman app could have 1 or even 0 processes running (at 0 it becomes similar to CGI, but presumably the process would stay around for some time to respond to subsequent requests). The "scaling down" scenario I often think about would be a email contact form -- one of those things that has to be an app, can be implemented and deployed separately from other aspects of the site, and yet it's clear waste of resources to keep a process always around to respond to such requests. Though it's actually someplace where CGI would work just fine; but lets say you don't want to educate the developer about when they might want to use other deployment strategies (which is a rather complex discussion really, that would be better avoided by providing one really good strategy and telling everyone to use it).
Why prefer forking to threads in this case?
Threading doesn't provide much isolation, so it's not really feasible for a multiuser situation. Well, Zope 2 managed it, but only with signficant heroics that also degrade the programming experience.
OTOH, I don't know if it's useful to optimize for situations where most of the website is static with small dynamic portions. In a practical sense dynamicism (of some sort) is almost the norm these days (at least if a programmer is involved). So one threaded process per client may be reasonable as well.
One of mod_webkit's underutilized features was the ability to drop .psp files anywhere, and have them processed in a single process. This is also possible with other configuration techniques (rewrite rules, LocationMatch, etc), but not popularized in other frameworks either. Probably in part because of the module/package orientation of Python, and it's less comfortable to be loading files from arbitrary locations. Explicit relative imports would be a real boon in this situation.
Oh, and that brings up another point -- separate processes mean separate sys.paths and other isolation. Managing sys.path is a total pain in the butt. And module reloads of course, but even ignoring that sys.path is still annoying.
-- Ian Bicking / [EMAIL PROTECTED] / http://blog.ianbicking.org _______________________________________________ Web-SIG mailing list Web-SIG@python.org Web SIG: http://www.python.org/sigs/web-sig Unsubscribe: http://mail.python.org/mailman/options/web-sig/archive%40mail-archive.com
