Question

How to profile python code under Google App Engine runtime python27?

In runtime python it was done by this code – python runtime:

from google.appengine.ext import webapp

class PageHandler(webapp.RequestHandler):
  def get(self):
    self.response.headers['Content-Type'] = 'text/plain'
    self.response.out.write('Hello, WebApp World!')

def real_main():
  application = webapp.WSGIApplication([('/', PageHandler)], debug=True)
  run_wsgi_app(application)

def profile_main():
  # This is the main function for profiling
  # We've renamed our original main() above to real_main()
  import cProfile, pstats, StringIO
  prof = cProfile.Profile()
  prof = prof.runctx('real_main()', globals(), locals())
  stream = StringIO.StringIO()
  stats = pstats.Stats(prof, stream=stream)
  stats.sort_stats('cumulative')
  logging.info("Profile data:\n%s", stream.getvalue())

if __name__ == "__main__":
    profile_main()

In runtime python27 is has to be done differently since there is no main calls – how to do the same thing – I want to switch to python27 but not without profiling. How to attach profiler in python27 – python27 runtime?

import webapp2

class PageHandler(webapp2.RequestHandler):
    def get(self):
        self.response.headers['Content-Type'] = 'text/plain'
        self.response.out.write('Hello, WebApp World!')

app = webapp2.WSGIApplication([('/', PageHandler)])

Answer 1

You can profile a WSGI app using WSGI middleware by inserting in your appengine_config.py:

import cProfile
import cStringIO
import logging
import pstats

def webapp_add_wsgi_middleware(app):

  def profiling_wrapper(environ, start_response):
    profile = cProfile.Profile()
    response = profile.runcall(app, environ, start_response)
    stream = cStringIO.StringIO()
    stats = pstats.Stats(profile, stream=stream)
    stats.sort_stats('cumulative').print_stats()
    logging.info('Profile data:\n%s', stream.getvalue())
    return response

  return profiling_wrapper