Blender plugin to rerun a Python script on change. Still buggy properly shutting down

blenderlivereload.py

from threading import Event, Thread
import bpy
from inotify_simple import INotify, flags
import traceback

# this is still buggy on properly cleaning things up on exit

def run(exit: Event, changed: Event, filename):
    inotify = INotify()
    inotify.add_watch(filename, flags.MODIFY)

    # wish we could do epoll over the event and the inotify fd
    while not exit.is_set():
        if inotify.read(500, 10):
            print(f'Changes to {filename}')
            changed.set()

# based on http://merwanachibet.net/blog/blender-long-running-python-scripts/
class FileWatcher(bpy.types.Operator):
    bl_description = 'Rerun a Python script on external change'
    bl_idname = 'aconz2.live_reload'
    bl_label = 'Live Reload a Python Script on Change'

    thread = None
    changed = Event()
    shouldexit = Event()
    timer = None
    filepath: bpy.props.StringProperty(subtype='FILE_PATH')  # gets magically set by fileselect_add

    def modal(self, context, event):
        if event.type == 'ESC':
            self.shouldexit.set()
            self.thread.join()
            context.window_manager.event_timer_remove(self.timer)
            return {'CANCELLED'}

        if event.type == 'TIMER':
            if self.changed.is_set():
                with open(self.filepath) as fh:
                    try:
                        print(f'Running {self.filepath}')
                        exec(compile(fh.read(), self.filepath, 'exec'), {})
                    except:
                        traceback.print_exc()
                self.changed.clear()

        return {'PASS_THROUGH'}

    def execute(self, context):
        print('filepath is ', self.filepath)
        self.changed.set()
        self.thread = Thread(target=run, args=(self.shouldexit, self.changed, self.filepath))
        self.thread.start()
        self.timer = context.window_manager.event_timer_add(0.1, window=context.window)
        context.window_manager.modal_handler_add(self)
        return {'RUNNING_MODAL'}

    def cancel(self, context):
        self.shouldexit.set()
        self.thread.join()
        context.window_manager.event_timer_remove(self.timer)

    def invoke(self, context, event):
        context.window_manager.fileselect_add(self)
        return {'RUNNING_MODAL'}

bl_info = {
    'name': 'Live Reload External Script',
    'blender': (2, 80, 0),
    'category': 'Development',
}

def register():
    bpy.utils.register_class(FileWatcher)

def unregister():
    bpy.utils.unregister_class(FileWatcher)

if __name__ == '__main__':
    register()
    bpy.ops.aconz2.live_reload('INVOKE_DEFAULT')

works for a bit and then fails, still buggy; WIP