FSEvents: Cannot watch the same path with two different observers about watchdog HOT 2 CLOSED

import os
import time

from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler


class FileModifiedHandler(FileSystemEventHandler):

    def __init__(self, path):
        self.observer = Observer()
        self.observer.schedule(self, path, recursive=True)
        self.observer.start()

    def on_modified(self, event):
        print(event)

    def stop(self):
        self.observer.stop()
        self.observer.join()


def main(n):
    path = '.'
    fhs = [FileModifiedHandler(path) for _ in range(0, n)]
    time.sleep(2)
    with open(os.path.join(path, 'temp.txt'), 'w') as f:
        f.write('hi')
    time.sleep(2)
    [fh.stop() for fh in fhs]


if __name__ == '__main__':
    print('this works:')
    main(1)  # OK
    print('this fails:')
    main(2)  # fails

this works:
<FileModifiedEvent: src_path='./temp.txt'>
this fails:
<FileModifiedEvent: src_path='./temp.txt'>
2016-05-31 19:03 Python[63998] (FSEvents.framework) FSEventStreamStop(): failed assertion 'streamRef != NULL'

2016-05-31 19:03 Python[63998] (FSEvents.framework) FSEventStreamInvalidate(): failed assertion 'streamRef != NULL'

2016-05-31 19:03 Python[63998] (FSEvents.framework) FSEventStreamRelease(): failed assertion 'streamRef != NULL'

Traceback (most recent call last):
  File "/Users/james/projects/experiments/watchdog_experiment/watchdog_experiment.py", line 38, in <module>
    main(2)  # fails
  File "/Users/james/projects/experiments/watchdog_experiment/watchdog_experiment.py", line 31, in main
    [fh.stop() for fh in fhs]
  File "/Users/james/projects/experiments/watchdog_experiment/watchdog_experiment.py", line 31, in <listcomp>
    [fh.stop() for fh in fhs]
  File "/Users/james/projects/experiments/watchdog_experiment/watchdog_experiment.py", line 20, in stop
    self.observer.stop()
  File "/Users/james/projects/experiments/watchdog_experiment/venv/lib/python3.4/site-packages/watchdog/utils/__init__.py", line 99, in stop
    self.on_thread_stop()
  File "/Users/james/projects/experiments/watchdog_experiment/venv/lib/python3.4/site-packages/watchdog/observers/api.py", line 357, in on_thread_stop
    self.unschedule_all()
  File "/Users/james/projects/experiments/watchdog_experiment/venv/lib/python3.4/site-packages/watchdog/observers/api.py", line 353, in unschedule_all
    self._clear_emitters()
  File "/Users/james/projects/experiments/watchdog_experiment/venv/lib/python3.4/site-packages/watchdog/observers/api.py", line 230, in _clear_emitters
    for emitter in self._emitters:
ValueError: PyCapsule_GetPointer called with invalid PyCapsule object

Process finished with exit code 1