izzzzzi / flask-threads

A helper library to work with threads in Flask

Flask-Threads

A helper library to work with threads within Flask applications.

The main problem that you face trying to spin a background thread or running a future in Flask app - is loosing the application context. The most common scenario is to try to access flask.g object. Application context is a thread local so you can not access it from another thread and Flask will raise an exception if you would try to.

This library provides helper classes that allows you accessing the current application context from another thread.

Warning! Alpha-version, use at your own risk.

Installation

$ pip install Flask-Threads

Examples

Threads

from flask import request
from flask import Flask
from flaskthreads import AppContextThread

app = Flask('my_app')


@app.route('/user')
def get_user():
    g.user_id = request.headers.get('user-id')
    t = AppContextThread(target=do_some_user_work_in_another_thread)
    t.start()
    t.join()
    return 'ok'


def do_some_user_work_in_another_thread():
    id = g.user_id
    print(id)

Concurrent futures

from flask import request
from flask import Flask
from flaskthreads import ThreadPoolWithAppContextExecutor

app = Flask('my_app')


@app.route('/user')
def get_user():
    g.user_id = request.headers.get('user-id')
    with ThreadPoolWithAppContextExecutor(max_workers=2) as pool:
        future = pool.submit(do_some_user_work_in_another_thread)
        future.result()
    return 'ok'


def do_some_user_work_in_another_thread():
    id = g.user_id
    print(id)