Multiprocessing-fork does not properly kill instances on stop/restart

[cnicodeme]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When restarting Sanic, some (forked) process might not be killed properly, causing them to stay alive and increasing the resouce usage (memory, cpu).

In the long run, after multiple restarts, this leads to a system becoming instable.

Here's a copy of the ps aux | grep [m]ultiproc command:

user     3317222  0.0  0.7 1397988 513156 ?      Sl   Aug21   4:33 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=18) --multiprocessing-fork
user     3317224  0.0  0.6 1227500 436072 ?      Sl   Aug21   3:22 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=20) --multiprocessing-fork
user     3317226  0.0  0.4 1257428 325252 ?      Sl   Aug21   2:18 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=22) --multiprocessing-fork
user     3317228  0.0  1.3 1496080 902568 ?      Sl   Aug21  12:32 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=24) --multiprocessing-fork
user     3317230  0.0  0.9 1256720 609312 ?      Sl   Aug21   7:53 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=26) --multiprocessing-fork
user     3317232  0.0  1.1 1390208 732892 ?      Sl   Aug21   8:20 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=28) --multiprocessing-fork
user     3317233  0.0  1.0 1441388 686740 ?      Sl   Aug21   6:40 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=30) --multiprocessing-fork
user     3317235 92.8  1.6 1480008 1053132 ?     Rl   Aug21 29348:51 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=32) --multiprocessing-fork
user     3317238  0.0  1.3 1433156 904704 ?      Sl   Aug21  11:20 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=34) --multiprocessing-fork
user     3317239  0.0  1.0 1273864 675260 ?      Sl   Aug21   9:42 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=36) --multiprocessing-fork
user     3317241  0.0  0.8 1338840 548328 ?      Sl   Aug21   5:52 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=39) --multiprocessing-fork
user     3317242  0.0  1.3 1368812 880972 ?      Sl   Aug21  14:40 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=64) --multiprocessing-fork
user     3868075  0.0  0.0  15044 11120 ?        S    Mar19   0:00 /var/www/project/env/bin/python -c from multiprocessing.resource_tracker import main;main(5)
user     3868076  2.4  0.0 1093636 41204 ?       Sl   Mar19 6260:56 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=8) --multiprocessing-fork
user     3868085  0.0  0.0  15044 10980 ?        S    Mar19   0:00 /var/www/project/env/bin/python -c from multiprocessing.resource_tracker import main;main(5)
user     3868086  2.5  0.0 1250296 61720 ?       Sl   Mar19 6382:19 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=8) --multiprocessing-fork
user     3868094  0.0  0.0  62500 37468 ?        S    Mar19   0:02 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=18) --multiprocessing-fork
user     3868095  0.0  0.0  62496 37180 ?        S    Mar19   0:28 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=20) --multiprocessing-fork
user     3868096  0.0  0.0  62496 37304 ?        S    Mar19   0:04 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=22) --multiprocessing-fork
user     3868097  0.0  0.0  62500 37212 ?        S    Mar19   0:01 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=24) --multiprocessing-fork
user     3868098  0.0  0.0  62496 37468 ?        S    Mar19   0:08 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=26) --multiprocessing-fork
user     3868099  0.0  0.0  62496 37520 ?        S    Mar19   0:06 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=28) --multiprocessing-fork
user     3868100  0.0  0.0  62504 37476 ?        S    Mar19   0:13 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=30) --multiprocessing-fork
user     3868101  0.0  0.0  62504 37468 ?        S    Mar19   0:18 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=32) --multiprocessing-fork
user     3868102  0.0  0.0  62492 37188 ?        S    Mar19   0:48 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=34) --multiprocessing-fork
user     3868103  0.0  0.0  62500 37456 ?        S    Mar19   1:05 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=36) --multiprocessing-fork
user     3868104  0.0  0.0  62496 37268 ?        S    Mar19   0:36 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=38) --multiprocessing-fork
user     3868105  0.0  0.0  62496 37228 ?        S    Mar19   1:29 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=40) --multiprocessing-fork
user     3868106  0.6  0.0  61112 34804 ?        S    Mar19 1555:37 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=42) --multiprocessing-fork
user     3868152  1.1  0.0  86668 56932 ?        S    Mar19 2815:44 /var/www/project/env/bin/python -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=42) --multiprocessing-fork

Code snippet

Sanic is started using Supervisor with the following script:

[program:myapp]
user = user
command=/var/www/myapp/env/bin/python /var/www/myapp/www/server.py --prod
autostart=true
autorestart=true
stopsignal=INT
startsecs=2
stopwaitsecs=5

And here's the content of server.py used by Supervisor (nothing fancy):

#!./env/bin/python
# -*- coding:utf-8 -*-

from app import App
import sys, os, argparse

sys.path.append(os.path.dirname(os.path.realpath(__file__)))

app = App().app

if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Start the Sanic[Fernand] server')
    args = parser.parse_args()

    autoreload = None

    app.run(**{
        'host': '127.0.0.1',
        'port': 5000,
        'dev': False,
        'access_log': False,
        'fast': True
    })

Expected Behavior

When stopping Sanic, all processes should be stopped, including the forked one.

How do you run Sanic?

Sanic CLI

Operating System

Linux

Sanic Version

23.12

Additional context

I'm not sure about the Sanic version because process were as old as March and at the time, we were using Sanic==23.12