Pystray does not work in subprocess if the module is imported in the parent process

Code:

from threading import Thread
from PIL import Image
import multiprocessing

import pystray
# import gi.overrides.Gtk or gi.repository.Gtk
 works too

def f():
    import pystray
    #from importlib import reload; reload(pystray)
    icon=pystray.Icon("Plover")
    icon.icon=Image.new("RGB", (10, 10), (255, 255, 255))
    icon.visible=True
    icon.run()

p=multiprocessing.Process(target=f)
p.start()
p.join()

Backend: PYSTRAY_BACKEND=appindicator

Issue: the icon is not displayed. However if the first import pystray line is commented out, the icon will be displayed.

importlib.reload doesn't fix the issue.

Version: latest git. Python version: 3.9.

Example run:

$ ./a.py 

[hang, doesn't show any tray icon. Interrupt the program]

^CTraceback (most recent call last):
  File "/tmp/./a.py", line 23, in <module>
    p.join()
  File "/usr/lib/python3.9/multiprocessing/process.py", line 149, in join
    res = self._popen.wait(timeout)
  File "/usr/lib/python3.9/multiprocessing/popen_fork.py", line 43, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
  File "/usr/lib/python3.9/multiprocessing/popen_fork.py", line 27, in poll
    pid, sts = os.waitpid(self.pid, flag)
KeyboardInterrupt
^CError in atexit._run_exitfuncs:
Traceback (most recent call last):
  File "/usr/lib/python3.9/multiprocessing/popen_fork.py", line 27, in poll
    pid, sts = os.waitpid(self.pid, flag)
KeyboardInterrupt

[After the process is interrupted and the cursor returns to the shell, wait for a long while...]

$ Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/gi/_error.py", line 31, in __init__
    def __init__(self, message='unknown error', domain='pygi-error', code=0):
KeyboardInterrupt
Process Process-1:
Traceback (most recent call last):
  File "/usr/lib/python3.9/multiprocessing/process.py", line 315, in _bootstrap
    self.run()
  File "/usr/lib/python3.9/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "/tmp/./a.py", line 19, in f
    icon.run()
  File "/tmp/pystray/lib/pystray/_base.py", line 192, in run
    self._run()
  File "/tmp/pystray/lib/pystray/_util/gtk.py", line 64, in _run
    self._notifier = notify_dbus.Notifier()
  File "/tmp/pystray/lib/pystray/_util/notify_dbus.py", line 40, in __init__
    self._notify = Gio.DBusProxy.new_sync(
RuntimeError: Converting the GError failed

moses-palmer / pystray

Pystray does not work in subprocess if the module is imported in the parent process #87