My apps all use webkit/0.96 django templates. Cold start times are
<10ms for handlers that don't use templates and closer to 50ms for
handlers that do.
On Mar 25, 2:50 pm, cz <czer...@gmail.com> wrote:
> Django is pretty resource intensive what with all the middleware and
> template processing so it makes sense that a more minimal app would be
> much faster. As for using .96 my guess is that you'd save ~180ms by
> skipping zipimport and a fair bit more by not having to compile all
> the imports (assuming the default GAE libraries are *.pyc). I'm still
> kind of a Python newbie (old Java/C++ prgmr) so this explanation might
> be completely wrong. Please post your results if you try it out!
> You're probably right about memcache, I was trying to figure out where
> all that extra response time (not startup time) came from on a cold
> start (500ms cold vs 10ms warm). Maybe it's just the Python
> interpreter having to compile all the response processing code.
> My app serves uploaded images and other longer term datastore
> blobjects, and using a Django view to serve them up is super slow when
> cold. I'm thinking of using the lighter weight webapp framework just
> to serve this kind of content. I didn't want to use more than one
> framework for the app, but it's probably worth it in this case. For
> lower traffic apps anyway.
> regards,
> - Claude
>
> On Mar 24, 11:58 pm, Robert <rjaa...@gmail.com> wrote:
>
> > Useful stuff, thanks!
>
> > Just yesterday I was looking into this same issue. I was wondering if
> > plain 0.96 Django use (without appengine helper or patch) would be
> > significantly faster, and your post really makes me want to try that.
> > I changed the handling of a single url in my app to be a "plain" GAE
> > (webapp.WSGIApplication) handler. This URL was for a cron-triggered
> > task that runs every minute. In the absence of other traffic this
> > resulted in a cold start every minute and this processing this trivial
> > request now only uses approx. 200 ms CPU quota. When it was part of
> > the main Django app, it would take over 2000 ms CPU quota.
>
> > BTW I'm fairly convinced that memcached data doesn't get flushed out.
>
> > On Mar 24, 6:27 am, cz <czer...@gmail.com> wrote:
>
> > > I added some timing code to see how expensive a cold app startup is.
> > > This is a Django1.x app so YMMV.
>
> > > The typical numbers are:
>
> > > Zipimport of Django: 180ms
> > > Appengine-django-helper monkeypatching: 430ms
> > > Misc imports, app-specific patching, etc: 20ms
> > > ------------------------------------------------------------------------
> > > Total app startup: 630ms
>
> > > This is for startup only, not the time it takes to then process the
> > > request, so this is a fixed expense. Also, this is real time not cpu
> > > quota time which is much higher.
>
> > > The biggest hog is the django-helper monkeypatcher. I'm eventually
> > > going to try appengine-patch with the hope that it will be faster.
>
> > > Additionally, on a cold startup my app processes a request in about
> > > 500ms, but on a warm app it only takes 10ms due to some aggressive
> > > caching. I think that when all your app instances expire so does all
> > > it's memcached data.
>
> > > If anybody has done something similar and found different numbers
> > > please post the results and let me know what I did wrong.
>
> > > Here's the main.py I'm using in case you'd like to point out any
> > > errors in my methodology:
> > > ----------------------------------------
>
> > > from time import clock
> > > t_main_start = clock()
>
> > > # Standard Python imports.
> > > import os
> > > import sys
> > > import logging
> > > import settings
>
> > > logging.getLogger().setLevel(settings.LOGGING_LEVEL)
>
> > > # Fix (hack) for missing unlink
> > > if os.name == 'nt':
> > > os.unlink = lambda: None
>
> > > # TODO (after gathering stats): remove this since appengine_django
> > > does it for us
> > > # Import Django 1.x from a zipfile and get rid of v.96.
> > > t_zip_start = clock()
> > > django_zip_path = os.path.abspath('django.zip')
> > > if django_zip_path not in sys.path:
> > > sys.path.insert(0, django_zip_path)
> > > for k in [k for k in sys.modules if k.startswith('django')]:
> > > del sys.modules[k]
> > > # TODO (after gathering stats): remove this line
> > > from django import template # provoke django zipimport
> > > t_zip = (clock() - t_zip_start) * 1000
>
> > > # Install appengine_django. Patches Django 1.x for use with GAE
> > > t_patch_start = clock()
> > > from appengine_django import InstallAppengineHelperForDjango
> > > InstallAppengineHelperForDjango()
> > > t_patch = (clock() - t_patch_start) * 1000
>
> > > # Patch the appengine_django patch to fix User object creation
> > > # Remove this when switching to appengine-patch
> > > from monkeypatch import patch
> > > patch()
>
> > > # Google App Engine imports.
> > > from google.appengine.ext.webapp import util
>
> > > # Import the part of Django that we use here.
> > > import django.core.handlers.wsgi
>
> > > t_main = (clock() - t_main_start) * 1000
> > > logging.info('[TIME] main.py startup: %.1fms (zipimport: %.1fms,
> > > appengine-django: %.1fms)' % (t_main,t_zip,t_patch))
>
> > > def real_main():
> > > t_request_start = clock()
> > > # Create a Django application for WSGI.
> > > application = django.core.handlers.wsgi.WSGIHandler()
>
> > > # Run the WSGI CGI handler with that application.
> > > util.run_wsgi_app(application)
> > > t_request = (clock() - t_request_start) * 1000
> > > logging.info('[TIME] request: %.1fms' % t_request)
>
> > > def profile_main():
> > > # Rename this to main() for profiling
> > > import cProfile, pstats
> > > prof = cProfile.Profile()
> > > prof = prof.runctx("real_main()", globals(), locals())
> > > print "<pre>"
> > > stats = pstats.Stats(prof)
> > > stats.sort_stats("time") # Or cumulative
> > > stats.print_stats(80) # 80 = how many to print
> > > # The rest is optional.
> > > #stats.print_callees()
> > > #stats.print_callers()
> > > print "</pre>"
>
> > > main = real_main
>
> > > if __name__ == '__main__':
> > > main()
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