[Question] Using vmprof with uwsgi

[devonhk]

I'd like to know if there is any way to use vmprof to profile a python web app in a production style environment.

Current problem I'd like to profile a flask app running with uwsgi.

Let's assume I have the following project directory:

.
├── app.py
├── uwsgi.ini
└── wsgi.py

And my wsgi.py module

from app import app_factory
app = app_factory('app.settings.defaults.Config')

I tried doing something like this to manually start/stop the profiler

import atexit
import os
import vmprof

from app import app_factory

fp = open("/tmp/vmprof.out-%s" % os.getpid(), "w")
vmprof.enable(fp.fileno(), warn=False)

app = app_factory('app.settings.defaults.Config')

def disable_at_exit():
     vmprof.disable()
     fp.close()

atexit.register(disable_at_exit)

And ran wsgi with this command uwsgi -http :8080 --wsgi-file uwsgi.py

Unfortunately uwsgi just returns 500 when performing any http request on localhost:8080.

Is the only way to run vmprof to call it through it's entry point like this python -m vmprof <module_to_be_profiled>?

[planrich]

Tried to reproduce your setup with python3.6. As you described it the uwsgi app could not hinge the application. The following worked:

app.py

import atexit
import os
import vmprof
# I removed the import of app_factory here flask 0.12 does not seem to export it
fp = open("/tmp/vmprof.out-%s" % os.getpid(), "a+") # only 'r' does not work, must be writable as well
vmprof.enable(fp.fileno())
from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, World!'

def disable_at_exit():
     vmprof.disable()
     fp.close()

atexit.register(disable_at_exit)

Then mount the application on the mountpoint: /yourapplication

uwsgi --http :8080 --wsgi-file uwsgi.py --mount /yourapplication=app:app

If that does not work for you I need more information to reproduce.

[methane]

AFAIK, vmprof uses SIGPROF. This option is required, maybe. http://uwsgi-docs.readthedocs.io/en/latest/Options.html#py-call-osafterfork