CODEWITHSUNDEEP
pythonasynchronousflask
Thanh Nguyen
Thanh Nguyen

Reputation: 5352

How to use flask context with concurrent.futures.ThreadPoolExecutor

I'm trying to make multiple requests async and get response back, I'm using concurrent.futures to do this, but inside my function using current_app which from flask and I always got this error:

RuntimeError: Working outside of application context.

I don't know how to resolve this. Can anyone please help?

Below are my code:

run.py:

import concurrent.futures
from flask import current_app
from http_calls import get_price, get_items

def init():
    with current_app._get_current_object().test_request_context():
        with concurrent.futures.ThreadPoolExecutor(max_workers=20) as executor:
            futs = []
            futs.append(executor.submit(get_price))
            futs.append(executor.submit(get_items))

            print([fut.result() for fut in concurrent.futures.as_completed(futs)])

init()

http_calls.py

from flask import current_app

def get_price():
    url = current_app.config['get_price_url']
    return requests.get(url).json()

def get_items():
    url = current_app.config['get_items_url']
    return requests.get(url).json()

Upvotes: 11

Views: 10588

Answers (3)

Jyothis Benny
Jyothis Benny

Reputation: 19

def with_app_context(cls, app, func):
    def wrapper(*args, **kwargs):
        with app.app_context():
            return func(*args, **kwargs)
    return wrapper

you can use wrapper for achieving this. you can call your function from thread pool like below

with concurrent.futures.ThreadPoolExecutor(max_workers=2) as executor:
                # download using wkhtmltopdf (helps to address access denied issues)
                res = executor.submit(with_app_context(app, cls.some_func))

Upvotes: 0

daveruinseverything
daveruinseverything

Reputation: 5167

I was running into similar issues around using concurrent.futures with Flask. I wrote Flask-Executor as a Flask-friendly wrapper for concurrent.futures to solve this problem. It may be an easier way for you to work with these two together.

Upvotes: 16

stamaimer
stamaimer

Reputation: 6475

You should import your Flask instance in your script. Use current_app under the app context. 

import concurrent.futures
from your_application import your_app  # or create_app function to return a Flask instance
from flask import current_app
from http_calls import get_price, get_items

def init():
    with your_app.app_context():
        with concurrent.futures.ThreadPoolExecutor(max_workers=20) as executor:
            ...

Upvotes: 3

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