RecursionError when trying to implement both __getattribute__/__setattr__ and _getitem__/__setitem__ in python class

I’m running into the dreaded RecursionError while trying to implement a class that essentially acts as a proxy between a private variable _threads. The idea is for the class to act as a thread-aware dictionary, dishing out the correct dictionary assigned to a specific thread for each call to the class instance.

Background (Feel free to skip it if you don’t care)

I found myself needing this while parallelizing some reporting code that spans across many functions originally accessing many (consistent) instance variables. The class is basically a way to avoid having to grab the current thread identity within each function and manually doing the lookup in an instance dictionary. Plus, for re-usability in other projects I figured why not!

Current Code

import threading

class ThreadManager(object):
    """
    A custom thread-aware class for managing multiple sets of variables
    without the need to keep track of the current, working thread
    """

    def __init__(self, *args, **kwargs):
        assert threading.current_thread() is threading.main_thread(), 
            "ThreadManager must be instantiated from MainThread"
        self._threads = dict()
        self._thread_vars = dict(**dict.fromkeys(args), **kwargs)

    @property
    def thread(self) -> dict:
        ident = self.thread_id
        if ident not in self._threads:
            # new thread, create new key/value pair with default thread_vars dict as value
            self._threads[ident] = self._thread_vars
        return self._threads[ident]

    @property
    def thread_id(self) -> int:
        return threading.current_thread().ident

    def update(self, data: dict) -> None:
        ident = self.thread_id
        for var, value in data.items():
            if var not in self._thread_vars:
                raise AttributeError("%r was not found in the list of original thread variables" % var)
            self._threads[ident][var] = value

    def clear(self) -> None:
        """Clears a single thread's variables and re-instates the default values"""
        ident = self.thread_id
        self._threads[ident].clear()
        self._threads[ident].update(self._thread_vars)

    # region dunders
    def __setattr__(self, var, value):
        """
        >>> tm = ThreadManager("a", "b", c=False)
        >>> tm.b
        >>> tm.b = "data"
        >>> tm.b
        "data"
        """
        print(f"__setattr__: var={var}, value={value}")
        _ = self.thread  # FIXME: Hacky way to ensure the thread and accompanying dict exist before updating it
        self._threads[self.thread_id][var] = value

    def __getattr__(self, var):
        """
        >>> tm = ThreadManager("a", "b", c=False)
        >>> tm.b
        >>> tm.c
        False
        """
        print(f"__getattr__: var={var}")
        return self.thread[var]

    def __setitem__(self, var, value):
        """
        >>> tm = ThreadManager("a", "b", c=False)
        >>> tm["b"]
        >>> tm["b"] = "data"
        >>> tm["b"]
        "data"
        """
        print(f"__setitem__: var={var}, value={value}")
        _ = self.thread  # FIXME: Hacky way to ensure the thread and accompanying dict exist before updating it
        self._threads[self.thread_id][var] = value

    def __getitem__(self, var):
        """
        >>> tm = ThreadManager("a", "b", c=False)
        >>> tm["b"]
        >>> tm["c"]
        False
        """
        print(f"__getitem__: var={var}")
        return self.thread[var]

    def __len__(self):
        """Total number of threads being managed"""
        return len(self._threads)
    # endregion

if __name__ == "__main__":
    tm = ThreadManager("a", "b", c={"d": 1})

Using the above code I end up with the RecursionError and traceback:

__setattr__: var=_threads, value={}
__getattr__: var=_threads
__getattr__: var=_threads
__getattr__: var=_threads
...
__getattr__: var=_threads
__getattr__: var=_threads
Traceback (most recent call last):
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 1266, in <module>
    tm = ThreadManager("a", "b", c={"d": 1})
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 87, in __init__
    self._threads = dict()
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 125, in __setattr__
    _ = self.thread  # FIXME: Hacky way to ensure the thread and accompanying dict exist before updating it
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 93, in thread
    if ident not in self._threads:
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 136, in __getattr__
    return self.thread[var]
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 93, in thread
    if ident not in self._threads:
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 136, in __getattr__
    return self.thread[var]
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 93, in thread
    if ident not in self._threads:
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 136, in __getattr__
    return self.thread[var]
...
  File "C:/Users/mhill/PycharmProjects/reporting/app/reports/base.py", line 100, in thread_id
    return threading.current_thread().ident
  File "C:UsersmhillAppDataLocalProgramsPythonPython37libthreading.py", line 1233, in current_thread
    return _active[get_ident()]
RecursionError: maximum recursion depth exceeded while calling a Python object

I’m trying to keep the abilities to both access the dictionary items as properties (using tm.property_name) and as you would a typical dictionary item (using tm["property_name"]), which is why I’m trying to implement both __getattribute__/__setattr__ and __getitem__/__setitem__

Can anyone offer any insight on how I can resolve this issue?