多处理；如何调试：_pickle.PicklingError:无法pickle对象，因为需要太深的递归

Question

我有一个可以使用Python代码运行的模拟，并希望使用stable-baselines3中的SubProcVecEnv创建它的多个实例。这使用子流程在不同的内核上运行模拟，在我对代码进行大量更改之前，它就已经工作了。但是，现在我收到下面的错误，不知道如何调试它，因为我不知道是哪部分代码导致了它。有没有办法找出哪个对象/方法导致递归深度被超过？我也不记得在代码中的任何地方写过递归方法。搜索错误消息失败

/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/site-packages/gym/logger.py:30: UserWarning: WARN: Box bound precision lowered by casting to float32
Traceback (most recent call last):
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/site-packages/cloudpickle/cloudpickle_fast.py", line 563, in dump
    return Pickler.dump(self, obj)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/site-packages/cloudpickle/cloudpickle_fast.py", line 639, in reducer_override
    if sys.version_info[:2] < (3, 7) and _is_parametrized_type_hint(obj):  # noqa  # pragma: no branch
RecursionError: maximum recursion depth exceeded in comparison

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/philipp/Code/ba_pw/train.py", line 84, in <module>
    venv = utils.make_venv(env_class, network, params, remote_ports, monitor_log_dir)
  File "/home/philipp/Code/ba_pw/sumo_rl/utils/utils.py", line 170, in make_venv
    return vec_env.SubprocVecEnv(env_fs)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/site-packages/stable_baselines3/common/vec_env/subproc_vec_env.py", line 106, in __init__
    process.start()
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/multiprocessing/process.py", line 121, in start
    self._popen = self._Popen(self)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/multiprocessing/context.py", line 291, in _Popen
    return Popen(process_obj)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/multiprocessing/popen_forkserver.py", line 35, in __init__
    super().__init__(process_obj)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/multiprocessing/popen_fork.py", line 19, in __init__
    self._launch(process_obj)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/multiprocessing/popen_forkserver.py", line 47, in _launch
    reduction.dump(process_obj, buf)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/multiprocessing/reduction.py", line 60, in dump
    ForkingPickler(file, protocol).dump(obj)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/site-packages/stable_baselines3/common/vec_env/base_vec_env.py", line 372, in __getstate__
    return cloudpickle.dumps(self.var)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/site-packages/cloudpickle/cloudpickle_fast.py", line 73, in dumps
    cp.dump(obj)
  File "/home/philipp/anaconda3/envs/sumo_rl/lib/python3.8/site-packages/cloudpickle/cloudpickle_fast.py", line 570, in dump
    raise pickle.PicklingError(msg) from e
_pickle.PicklingError: Could not pickle object as excessively deep recursion required.

Answer 1

我最终用the answer to this question找到了一个解决方案：

我看起来像是要酸洗的对象有太多层。我打电话：

sys.setrecursionlimit(3000)

现在它开始工作了