python看门狗模块不能与redhat服务器下的django/mod_wsgi一起工作

Question

我们使用django（1.7.5）mod_wsgi在redhat服务器的apache2下，并尝试使用watchdog来监控文件。

它在本地使用pythonmanager.pyrunserver命令运行良好，而当我将其部署到产品环境时，事件不会在wsgi模式下触发

# wsgi.py
from django.core.wsgi import get_wsgi_application
application = get_wsgi_application()

LOGGER.debug("Starting to watch for config file changes.")
fw = FileWatcher()

# filewatcher
path = settings.PROJECT_ROOT
filename = 'config.json'
class ConfigHandler(FileSystemEventHandler):
    def on_modified(self, event):
        if not event.is_directory and event.src_path.endswith(filename):
            LOGGER.debug("The config has changed!, Reloading")

class FileWatcher(object):

    _instance = None
    _watching = False

    def __new__(cls, *args, **kwargs):
        if not cls._instance:
            LOGGER.debug("Creating new FileWatcher")
            cls._instance = super(FileWatcher, cls).__new__(cls, *args, **kwargs)

            cls.start_watching()

        return cls._instance

    @classmethod
    def start_watching(cls):
        if not cls._watching:
            LOGGER.debug("Starting to monitor the file: %s",
                        os.path.join(path, filename))
            event_handler = ConfigHandler()
            observer = Observer()
            observer.schedule(event_handler, path=path, recursive=False)
            observer.start()

            cls._watching = True

Answer 1

找到路由原因，默认的观察者（inotify.InotifyObserver）在具有旧linux内核的旧redhat服务器中不工作

它在http://pythonhosted.org/watchdog/api.html#module-watchdog.observers

inotify.InotifyObserver Linux 2.6.13+   inotify(7) based observer
polling.PollingObserver Any fallback implementation

所以我把它改成了通用的

    from watchdog.observers.polling import PollingObserver
    # http://pythonhosted.org/watchdog/api.html#module-watchdog.observers
    observer = PollingObserver()