How can I make a permanent (between restarts) set or any other object

persistentset.py

from threading import Lock
import os, os.path
try:
    import dill as pickle
    import dill.settings
    from dill import FILE_FMODE
    dill.settings.update({'byref': True, 'fmode': FILE_FMODE, 'recurse': True, 'ignore': True})
except ImportError:
    import pickle

class PersistentSet(set):
    def __init__(self, setname, arg=()):
        self.setname = setname
        if len(arg):
            super().__init__(arg)
        self._load()

    def _load(self):
        if not os.path.isfile(self.setname) or os.path.getsize(self.setname) < 5:
            return None
        with open(self.setname, "rb") as f:
            self.update(pickle.load(f))

    def _dump(self):
        with Lock():
            with open(self.setname, "wb") as f:
                pickle.dump(set(self), f)
                os.fsync(f)

    def add(self, arg):
        super().add(pickle.loads(pickle.dumps(arg)))
        self._dump()

    def discard(self, arg):
        super().discard(pickle.loads(pickle.dumps(arg)))
        self._dump()

    def update(self, arg):
        super().update(pickle.loads(pickle.dumps(arg)))
        self._dump()

    def clear(self):
        super().clear()
        self._dump()

    def pop(self):
        r = super().pop()
        self._dump()
        return r
        

if __name__ == "__main__":
    ps = PersistentSet("ps", (1,2,3))
    ps.update((4,5,6))
    for item in ps:
        print(item)
    ps.discard(5)
    ps.pop()
    ps.add(10)
    assert len(ps) >= 5

requirements.txt

dill