Middleware for dumping the effect of each view to the RSS memory usage

django_debug_memory.py

"""Django Middleware for printing view's RSS usage after each request

Code for retrieving process memory information adapted from
http://code.activestate.com/recipes/286222-memory-usage/

"""

import inspect
import os


_scale = {'kb': 1024.0, 'mb': 1024.0 * 1024.0}


def resident():
     # read pseudo file  /proc/<pid>/status
    stat = open('/proc/{0}/status'.format(os.getpid())).read()
     # get VmRSS line e.g. 'VmRSS:  9999  kB\n ...'
    offset = stat.index('VmRSS:')
    value, unit = stat[offset:].split(None, 3)[1:3]  # whitespace
    return float(value) * _scale[unit.lower()]


class DebugMemoryMiddleware(object):
    debug_format = ('{delta:+8.1f}KiB  '
                    '{rss:5.1f}MiB  '
                    '{view_filename}:{view_name}(\n'
                    '{indent}request,\n'
                    '{indent}{args})')
    indent = 27 * ' '

    def process_response(self, request, response):
        rss = resident()
        arglist = [repr(arg) for arg in self.view_args]
        kwlist = ['{0}={1!r}'.format(k, v)
                  for k, v in self.view_kwargs.items()]
        print self.debug_format.format(
            delta=(rss - self.rss_before_view) / _scale['kb'],
            rss=rss / _scale['mb'],
            uri=request.META['PATH_INFO'],
            view_filename=self.view_filename,
            view_name=self.view_name,
            args=',\n{0}'.format(self.indent).join(arglist + kwlist),
            indent=self.indent)
        return response

    def process_view(self, request, callback, callback_args, callback_kwargs):
        # pylint: disable=W0613
        #         Unused argument
        # pylint: disable=W0201
        #         Attribute defined outside __init__
        self.rss_before_view = resident()
        try:
            self.view_filename = callback.func_code.co_filename
            self.view_name = callback.func_name
        except AttributeError:
            self.view_filename = inspect.getfile(callback.__class__)
            self.view_name = callback.__class__.__name__ + '.__call__'
        self.view_args = callback_args
        self.view_kwargs = callback_kwargs