Python, profiling

'Have you seen python web developers who do high load site development for living?'
'Oh, almost all of them do such things,' you say.
'Have you seen python devs who know how to debug?'
'A few,' you say.
'Have you seen python devs who profile things that supposed to be high loaded?'

Python has cProfile, C has kcachegrind, they look good together.

For instance, lets profile multithreaded wsgi app. Change your handler

def read(self, request, *args, **kwargs):
    ...
    return ...

To something like

def read(self, *args, **kwargs):
    import cProfile
    import uuid
    cProfile.runctx('self.read2(*args, **kwargs)', globals(), locals(),
        '/folder_with_stats/' + uuid.uuid4().get_hex())
    return self.__res

def read2(self, *args, **kwargs):
    self.__res = self.read3(*args, **kwargs)

def read3(self, request, *args, **kwargs):
    ...
    return ...

Then (high) load your app. Gather results from folder_with_stats

import os
import pstats
import time
from pyprof2calltree import convert

# Collect stats
p = None
for i in os.listdir('/folder_with_stats'):
    filename = '/folder_with_stats/' + i
    if not p:
        p = pstats.Stats(filename)
    else:
        p.add(filename)
    os.unlink(filename)
res = str(int(time.time())) + '.kgrind'
convert(p, res)

os.execlp('kcachegrind', res)

The main thing here to note is pyprof2calltree. The result