This Django middleware can be used to collect and print accumulated profiling statistics on a running site. As opposed to popular individual view profiling tools this one profiles all existing views as they are being executed and saves statistics for later usage. On production (DEBUG=False) only each 20-th request is profiled to keep CPU overhead low.
Usage
- Save to profile.py
- Add 'profile.ProfileMiddleware' to MIDDLEWARE_CLASSES
- ...run requests
- Visit http://mysite/profile/ to print accumulated statistics
- Visit http://mysite/myview?profile to profile this view only and print statistics immediately
Listing
from cStringIO import StringIO
from django.conf import settings
from django.http import HttpResponse
from os import path
from random import randrange
import cProfile
import pstats
# see pstats.Stats.print_stats
RESTRICTIONS = 30,
# to keep stats in memory
STATS_FILE = None
# to dump accumulated stats to file after every request
STATS_FILE = '/tmp/mysite.profile'
class ProfileMiddleware(object):
empty = True
prof = cProfile.Profile()
def process_request(self, request):
if request.path.startswith('/profile/'):
# return collected stats
if not (settings.DEBUG or request.user.is_staff):
return HttpResponseForbidden(
'Forbidden', content_type='text/plain')
return self.print_stats()
def process_response(self, request, response):
return response
def process_view(self, request, callback, callback_args, callback_kwargs):
if 'profile' in request.GET:
# profile this view and print results
self.prof.clear()
self.prof.runcall(
callback, request, *callback_args, **callback_kwargs)
self.empty = False
return self.print_stats(None)
if not self.empty and not settings.DEBUG and randrange(20):
# run without profiling
return callback(request, *callback_args, **callback_kwargs)
# run with profiling
self.empty = False
if STATS_FILE:
self.prof.clear()
retval = self.prof.runcall(
callback, request, *callback_args, **callback_kwargs)
if STATS_FILE:
# merge stats
self.save()
return retval
def save(self):
stats = pstats.Stats(self.prof)
stats.strip_dirs()
if path.exists(STATS_FILE):
try:
stats.add(STATS_FILE)
except (EOFError, ValueError):
pass
stats.dump_stats(STATS_FILE)
def print_stats(self, input_file=STATS_FILE):
# handle ourselfves
out = StringIO()
if input_file:
stats = pstats.Stats(input_file, stream=out)
else:
if self.empty:
return HttpResponse('No data yet.', content_type='text/plain')
stats = pstats.Stats(self.prof, stream=out).strip_dirs()
stats.sort_stats('cumulative').print_stats(*RESTRICTIONS)
stats_str = out.getvalue()
return HttpResponse(stats_str, content_type='text/plain')
