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im currently facing an issue with eel and multiprocessing opening multiple eel windows when an external python script executes that uses multiprocessing.

Folder Structure

Project[folder]
           |
        start.py
           |_______web[folder]
                          |_______partials[folder]
                                              |
                                           partial.py

From start.py(script that starts my app) i import partial.py as i use its functionality in part part of the application and for speed requires the use of multiprocessing.

Code snippet(s)

START.PY (putting a snippet as its way to long)

import eel
#import ... other imports(NO multiprocessing here)
sys.path.append(os.getcwd() + "/web/partials/")
import partials

#... several non relevant @eel.exposed functions are here...

APP ={#...dict with all the keys seen below...}

if __name__ == "__main__":
    try:
        # Start the application and pass all initial params below from APP dict
        eel.start(APP["start_html"], host=APP["host"], size=APP["size"], mode=APP["mode"], port=APP["port"])
    except (SystemExit, MemoryError, KeyboardInterrupt):
        # Handle bottle errors, in all cases call a function close of all remaining windows
        close_handler()
...

PARTIAL.PY 

import eel
import os
import re
import socket
import ntc_templates
from mac_vendor_lookup import MacLookup, BaseMacLookup
import netmiko
from netmiko import Netmiko, NetMikoAuthenticationException, NetMikoTimeoutException
import concurrent.futures


def device_details_builder_mp():
    #... code that will run with multiprocessing from every entry in device_data below...


@eel.expose
def device_details_search(site, user, password, device_data):
    # Init list that will hold all the final data
    final_device_details = []

    with concurrent.futures.ProcessPoolExecutor() as executor_detail:
        results_details = [executor_detail.submit(device_details_builder_mp, device, site, user, password) for device in device_data]

        for result_detail in concurrent.futures.as_completed(results_details):
            final_device_details.append(result_detail.result())

Issue

So i think my issue is the way im importing partial.py into start.py, if i run start.py and use the app and trigger the feature that uses multiprocessing which gets called from the java-script side it just works.

The issue happens when i pack the app and execute it from an .exe when i use the feature that use multiprocessing it doesn't work and it opens multiple eel windows, Was reading that multiprocessing re imports everything again but i couldn't figure that out exatly, i saw this as well: https://github.com/samuelhwilliams/Eel/issues/224

Hoping someone can assist me in how to better import partial.py into start.py so it doesn't cause the issue with multiprocessing.

Thanks

Desktop

  • OS: Windows 10 1809
  • Browser: Brave
  • Version: EEL 0.12.4
Alejandro Suarez
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  • What is the unwanted behavior? Do you have an error message or something? – Tom Nijhof Jun 05 '20 at 06:17
  • There are no errors necessarily, the unwanted behavior is that when the multiprocessing function is triggered, i get multiple windows of the eel app open up as if the code line eel.start(...) was being run multiple times, but is only meant to run once to open the application initially and never again. The application is already open when this happens, i have a search feature in it that use multiprocessing when u click search multiple eel windows spawn. – Alejandro Suarez Jun 06 '20 at 02:01
  • I don't see the threading in your code. They way I did it was by having an function exposed to eel, that function started a thread. I had an other function what could stop the thread (that was needed for my use case). As long as you don't have the starting of eel in the thread you will get one instance – Tom Nijhof Jun 06 '20 at 15:21
  • I choose to skip it cause it wasnt relevant to the situation, i kinda knew it wasnt the mp code itself. Turned out to be PyInstaller, did as the answer below and it now works for me. – Alejandro Suarez Jun 06 '20 at 19:18

1 Answers1

2

That time when a single line does it.

Added multiprocessing.freeze_support() in the if name == "main": and after packing, multiprocessing works fine.

I wasnt looking in the right place, it was not an eel issue but a PyInstaller one

https://github.com/pyinstaller/pyinstaller/wiki/Recipe-Multiprocessing#additional-code-for-pyinstaller--33-and-windows

Alejandro Suarez
  • 149
  • 3
  • 16