profiler.py
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"""
Application Profiler
====================
This module provides a middleware that profiles each request with the
:mod:`cProfile` module. This can help identify bottlenecks in your code
that may be slowing down your application.
.. autoclass:: ProfilerMiddleware
:copyright: 2007 Pallets
:license: BSD-3-Clause
"""
from __future__ import print_function
import os.path
import sys
import time
from pstats import Stats
try:
from cProfile import Profile
except ImportError:
from profile import Profile
class ProfilerMiddleware(object):
"""Wrap a WSGI application and profile the execution of each
request. Responses are buffered so that timings are more exact.
If ``stream`` is given, :class:`pstats.Stats` are written to it
after each request. If ``profile_dir`` is given, :mod:`cProfile`
data files are saved to that directory, one file per request.
The filename can be customized by passing ``filename_format``. If
it is a string, it will be formatted using :meth:`str.format` with
the following fields available:
- ``{method}`` - The request method; GET, POST, etc.
- ``{path}`` - The request path or 'root' should one not exist.
- ``{elapsed}`` - The elapsed time of the request.
- ``{time}`` - The time of the request.
If it is a callable, it will be called with the WSGI ``environ``
dict and should return a filename.
:param app: The WSGI application to wrap.
:param stream: Write stats to this stream. Disable with ``None``.
:param sort_by: A tuple of columns to sort stats by. See
:meth:`pstats.Stats.sort_stats`.
:param restrictions: A tuple of restrictions to filter stats by. See
:meth:`pstats.Stats.print_stats`.
:param profile_dir: Save profile data files to this directory.
:param filename_format: Format string for profile data file names,
or a callable returning a name. See explanation above.
.. code-block:: python
from werkzeug.middleware.profiler import ProfilerMiddleware
app = ProfilerMiddleware(app)
.. versionchanged:: 0.15
Stats are written even if ``profile_dir`` is given, and can be
disable by passing ``stream=None``.
.. versionadded:: 0.15
Added ``filename_format``.
.. versionadded:: 0.9
Added ``restrictions`` and ``profile_dir``.
"""
def __init__(
self,
app,
stream=sys.stdout,
sort_by=("time", "calls"),
restrictions=(),
profile_dir=None,
filename_format="{method}.{path}.{elapsed:.0f}ms.{time:.0f}.prof",
):
self._app = app
self._stream = stream
self._sort_by = sort_by
self._restrictions = restrictions
self._profile_dir = profile_dir
self._filename_format = filename_format
def __call__(self, environ, start_response):
response_body = []
def catching_start_response(status, headers, exc_info=None):
start_response(status, headers, exc_info)
return response_body.append
def runapp():
app_iter = self._app(environ, catching_start_response)
response_body.extend(app_iter)
if hasattr(app_iter, "close"):
app_iter.close()
profile = Profile()
start = time.time()
profile.runcall(runapp)
body = b"".join(response_body)
elapsed = time.time() - start
if self._profile_dir is not None:
if callable(self._filename_format):
filename = self._filename_format(environ)
else:
filename = self._filename_format.format(
method=environ["REQUEST_METHOD"],
path=(
environ.get("PATH_INFO").strip("/").replace("/", ".") or "root"
),
elapsed=elapsed * 1000.0,
time=time.time(),
)
filename = os.path.join(self._profile_dir, filename)
profile.dump_stats(filename)
if self._stream is not None:
stats = Stats(profile, stream=self._stream)
stats.sort_stats(*self._sort_by)
print("-" * 80, file=self._stream)
print("PATH: {!r}".format(environ.get("PATH_INFO", "")), file=self._stream)
stats.print_stats(*self._restrictions)
print("-" * 80 + "\n", file=self._stream)
return [body]