Re: Using a background thread with asyncio/futures with flask

[Lars Liedtke via Python-list]

Sorry, must have missed that :-/


Lars Liedtke
Lead Developer

[Tel.]  +49 721 98993-
[Fax]   +49 721 98993-
[E-Mail]l...@solute.de<mailto:l...@solute.de>


solute GmbH
Zeppelinstraße 15
76185 Karlsruhe
Germany

[Marken]

Geschäftsführer | Managing Director: Dr. Thilo Gans, Bernd Vermaaten
Webseite | www.solute.de <http://www.solute.de/>
Sitz | Registered Office: Karlsruhe
Registergericht | Register Court: Amtsgericht Mannheim
Registernummer | Register No.: HRB 748044
USt-ID | VAT ID: DE234663798



Informationen zum Datenschutz | Information about privacy policy
https://www.solute.de/ger/datenschutz/grundsaetze-der-datenverarbeitung.php




Am 22.03.24 um 08:58 schrieb Chris Angelico via Python-list:

On Fri, 22 Mar 2024 at 18:35, Lars Liedtke via Python-list
<mailto:python-list@python.org> wrote:



Hey,

As far as I know (might be old news) flask does not support asyncio.

You would have to use a different framework, like e.g. FastAPI or similar. Maybe someone 
has already written "flask with asyncio" but I don't know about that.




Did you try searching their documentation?

https://flask.palletsprojects.com/en/3.0.x/async-await/

ChrisA

--
https://mail.python.org/mailman/listinfo/python-list

Re: Using a background thread with asyncio/futures with flask

[Lars Liedtke via Python-list]

Hey,

As far as I know (might be old news) flask does not support asyncio.

You would have to use a different framework, like e.g. FastAPI or similar. Maybe someone 
has already written "flask with asyncio" but I don't know about that.

Cheers

Lars


Lars Liedtke
Lead Developer

[Tel.]  +49 721 98993-
[Fax]   +49 721 98993-
[E-Mail]l...@solute.de


solute GmbH
Zeppelinstraße 15
76185 Karlsruhe
Germany

[Marken]

Geschäftsführer | Managing Director: Dr. Thilo Gans, Bernd Vermaaten
Webseite | www.solute.de 
Sitz | Registered Office: Karlsruhe
Registergericht | Register Court: Amtsgericht Mannheim
Registernummer | Register No.: HRB 748044
USt-ID | VAT ID: DE234663798



Informationen zum Datenschutz | Information about privacy policy
https://www.solute.de/ger/datenschutz/grundsaetze-der-datenverarbeitung.php




Am 20.03.24 um 09:22 schrieb Thomas Nyberg via Python-list:

Hello,

I have a simple (and not working) example of what I'm trying to do. This is a 
simplified version of what I'm trying to achieve (obviously the background 
workers and finalizer functions will do more later):

`app.py`

```
import asyncio
import threading
import time
from queue import Queue

from flask import Flask

in_queue = Queue()
out_queue = Queue()


def worker():
   print("worker started running")
   while True:
   future = in_queue.get()
   print(f"worker got future: {future}")
   time.sleep(5)
   print("worker sleeped")
   out_queue.put(future)


def finalizer():
   print("finalizer started running")
   while True:
   future = out_queue.get()
   print(f"finalizer got future: {future}")
   future.set_result("completed")
   print("finalizer set result")


threading.Thread(target=worker, daemon=True).start()
threading.Thread(target=finalizer, daemon=True).start()

app = Flask(__name__)


@app.route("/")
async def root():
   future = asyncio.get_event_loop().create_future()
   in_queue.put(future)
   print(f"root put future: {future}")
   result = await future
   return result


if __name__ == "__main__":
   app.run()
```

If I start up that server, and execute `curl http://localhost:5000`, it prints 
out the following in the server before hanging:

```
$ python3 app.py
worker started running
finalizer started running
* Serving Flask app 'app'
* Debug mode: off
WARNING: This is a development server. Do not use it in a production 
deployment. Use a production WSGI server instead.
* Running on http://127.0.0.1:5000
Press CTRL+C to quit
root put future: 
worker got future: 
worker sleeped
finalizer got future: 
finalizer set result
```

Judging by what's printing out, the `final result = await future` doesn't seem 
to be happy here.

Maybe someone sees something obvious I'm doing wrong here? I presume I'm mixing 
threads and asyncio in a way I shouldn't be.

Here's some system information (just freshly installed with pip3 install 
flask[async] in a virtual environment for python version 3.11.2):

```
$ uname -a
Linux x1carbon 6.1.0-18-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.76-1 
(2024-02-01) x86_64 GNU/Linux

$ python3 -V
Python 3.11.2

$ pip3 freeze
asgiref==3.7.2
blinker==1.7.0
click==8.1.7
Flask==3.0.2
itsdangerous==2.1.2
Jinja2==3.1.3
MarkupSafe==2.1.5
Werkzeug==3.0.1
```

Thanks for any help!

Cheers,
Thomas
--
https://mail.python.org/mailman/listinfo/python-list

Re: pip-sync

[Lars Liedtke via Python-list]

Did maybe pip-sync create the venv with --system-site-packages (at least that's 
the commandline option for pip)

I only saw behaviour like this so far, when my venv was with 
--system-site-packages and a package was installed by the system.

Sorry for the first mess.
Cheers

Lars


Lars Liedtke
Senior Software Developer

[Tel.]
[Fax]   +49 721 98993-
[E-Mail]l...@solute.de


solute gmbh
Zeppelinstraße 15
76185 Karlsruhe
Germany


[Logo Solute]

Marken der solute gmbh | brands of solute gmbh
[Marken]

Triff uns auf der DMEXCO am 20. und 21. September in Köln und sichere dir die 
Chance auf eine brandneue Apple-Watch bei unserer Live-Auslosung!
Vereinbare hier einen Termin mit uns: 
https://outlook.office365.com/owa/calendar/solutedme...@o365.solute.de/bookings/

[dmexco 
Banner]

Geschäftsführer | Managing Director: Dr. Thilo Gans, Bernd Vermaaten
Webseite | www.solute.de 
Sitz | Registered Office: Karlsruhe
Registergericht | Register Court: Amtsgericht Mannheim
Registernummer | Register No.: HRB 110579
USt-ID | VAT ID: DE234663798



Informationen zum Datenschutz | Information about privacy policy
https://www.solute.de/ger/datenschutz/grundsaetze-der-datenverarbeitung.php


Am 21.07.23 um 20:08 schrieb Larry Martell via Python-list:

I am trying to set up and maintain a venv with pip-sync. On my bare
metal I have the apparmor python package installed, but it is not
installed in my venv and it's not in my requirements file. When I run
pip-sync I get:

Found existing installation: apparmor 2.13.3
ERROR: Cannot uninstall 'apparmor'. It is a distutils installed
project and thus we cannot accurately determine which files belong to
it which would lead to only a partial uninstall.

Since it's not installed in the venv why does it want to uninstall it?

--
https://mail.python.org/mailman/listinfo/python-list

Re: pip-sync

[Lars Liedtke via Python-list]

This email contains a secure message that can be read by opening the attachment.





Lars Liedtke
Senior Software Developer

[Tel.]
[Fax]   +49 721 98993-
[E-Mail]l...@solute.de


solute gmbh
Zeppelinstraße 15
76185 Karlsruhe
Germany


[Logo Solute]

Marken der solute gmbh | brands of solute gmbh
[Marken]

Triff uns auf der DMEXCO am 20. und 21. September in Köln und sichere dir die 
Chance auf eine brandneue Apple-Watch bei unserer Live-Auslosung!
Vereinbare hier einen Termin mit uns: 
https://outlook.office365.com/owa/calendar/solutedme...@o365.solute.de/bookings/

[dmexco 
Banner]

Geschäftsführer | Managing Director: Dr. Thilo Gans, Bernd Vermaaten
Webseite | www.solute.de 
Sitz | Registered Office: Karlsruhe
Registergericht | Register Court: Amtsgericht Mannheim
Registernummer | Register No.: HRB 110579
USt-ID | VAT ID: DE234663798



Informationen zum Datenschutz | Information about privacy policy
https://www.solute.de/ger/datenschutz/grundsaetze-der-datenverarbeitung.php

--- Begin Message ---
Did maybe pip-sync create the venv with --system-site-packages (at least 
that's the commandline option for pip)


I only saw behaviour like this so far, when my venv was with 
--system-site-packages and a package was installed by the system.


Cheers

Lars

Am 21.07.23 um 20:08 schrieb Larry Martell via Python-list:

I am trying to set up and maintain a venv with pip-sync. On my bare
metal I have the apparmor python package installed, but it is not
installed in my venv and it's not in my requirements file. When I run
pip-sync I get:

Found existing installation: apparmor 2.13.3
ERROR: Cannot uninstall 'apparmor'. It is a distutils installed
project and thus we cannot accurately determine which files belong to
it which would lead to only a partial uninstall.

Since it's not installed in the venv why does it want to uninstall it?


OpenPGP_signature
Description: OpenPGP digital signature
--- End Message ---
-- 
https://mail.python.org/mailman/listinfo/python-list

Re: Best practices for using super()

[Lars Liedtke via Python-list]

Hey,

When you have multiple inheritance and you e.g. want to explicitely call 
__init__ of one of the classes inherited from, that is not the first in the 
list of classes to inherit from.

Cheers,

Lars


Lars Liedtke
Senior Software Developer

[Tel.]  +49 721 98993-
[Fax]   +49 721 98993-
[E-Mail]l...@solute.de


solute GmbH
Zeppelinstraße 15
76185 Karlsruhe
Germany


[Logo Solute]


Marken der solute GmbH | brands of solute GmbH
[Marken]
[Advertising Partner]

Geschäftsführer | Managing Director: Dr. Thilo Gans, Bernd Vermaaten
Webseite | www.solute.de 
Sitz | Registered Office: Karlsruhe
Registergericht | Register Court: Amtsgericht Mannheim
Registernummer | Register No.: HRB 110579
USt-ID | VAT ID: DE234663798



Informationen zum Datenschutz | Information about privacy policy
https://www.solute.de/ger/datenschutz/grundsaetze-der-datenverarbeitung.php




Am 04.07.23 um 14:20 schrieb Peter Slížik via Python-list:

As a follow-up to my yesterday's question - are there any recommendations
on the usage of super()?

It's clear that super() can be used to invoke parent's:
- instance methods
- static methods
- constants ("static" attributes in the parent class, e.g. super().NUMBER).

This all works, but are there situations in which calling them explicitly
using a parent class name is preferred?

Best regards,
Peter

--
https://mail.python.org/mailman/listinfo/python-list