PATHOS: Pool not running with same class object PYTHON

Question

A pool is spawned and run within a context manager. I created an object of a class that calls a function which creates a pool to do some operations The pool iteration works smoothly when the function is called via that object but using the same object and calling the same function crashes giving an error "pool not running"

Implementation:

class ETLJob(SomeClass):
    def __init__(self):
        super().__init__()
        self.conf = None
    
    def fetch_data(self):
        """Override the Data Processing Function

        Returns:
            None: Void
        """
        return None

    def transform_data(self):
        """Override the Data Processing Function

        Returns:
            None: Void
        """
        return None

    def ingest_single(self):
        """Override the single Data Point Ingestion Function
        Ingest a single datapoint into the DB using API calls

        Returns:
            None: Void
        """
        return None

    @staticmethod
    def bulk_ingest(func: Callable[[dict], None], conf: list) -> None:
        """Bulk ingest SPIRE harvested data.

        Args:
            func (Callable[[dict], None]): Single data point ingest function
            conf (list): The client and plant configuration list

        Returns:
            None: Since this directly ingest data into DB

        Usage:
        ```py
        self.bulk_ingest(self.ingest_single, self.conf)
        ```
        """
        with ProcessPool(nodes=pathos.helpers.cpu_count() * 2) as pool:
            pool.map(func, conf)
            pool.close()
            pool.join()


if __name__ == "__main__":
    sp = ETLJob()
    sp.bulk_ingest(sp.ingest_single,sp.conf[:10])
    sp.bulk_ingest(sp.ingest_single,sp.conf[20:30])

Error Trace:

2022-05-20 10:51:29 | [INFO]:root - ERROR ingesting data for Client: 20 Plant: 20 @ Source: spire_actual
 Message: Not able to connect to database either client id is wrong or not found.
2022-05-20 10:51:29 | [INFO]:root - ERROR ingesting data for Client: 20 Plant: 18 @ Source: spire_actual
 Message: Not able to connect to database either client id is wrong or not found.
2022-05-20 10:51:29 | [INFO]:root - ERROR ingesting data for Client: 20 Plant: 17 @ Source: spire_actual
 Message: Not able to connect to database either client id is wrong or not found.
2022-05-20 10:51:29 | [INFO]:root - ERROR ingesting data for Client: 20 Plant: 19 @ Source: spire_actual
 Message: Not able to connect to database either client id is wrong or not found.
2022-05-20 10:51:30 | [INFO]:root - ERROR ingesting data for Client: 20 Plant: 21 @ Source: spire_actual
 Message: Not able to connect to database either client id is wrong or not found.
Traceback (most recent call last):
  File "/home/kayvan/projects/weather-repo/weather_combiner/data_pipelines/spire.py", line 596, in <module>
    s.bulk_ingest(s.ingest_single, s.conf[30:35])
  File "/home/kayvan/projects/weather-repo/weather_combiner/data_pipelines/spire.py", line 189, in bulk_ingest
    pool.map(func, conf)
  File "/home/kayvan/projects/weather/lib/python3.9/site-packages/pathos/multiprocessing.py", line 139, in map
    return _pool.map(star(f), zip(*args)) # chunksize
  File "/home/kayvan/projects/weather/lib/python3.9/site-packages/multiprocess/pool.py", line 364, in map
    return self._map_async(func, iterable, mapstar, chunksize).get()
  File "/home/kayvan/projects/weather/lib/python3.9/site-packages/multiprocess/pool.py", line 473, in _map_async
    self._check_running()
  File "/home/kayvan/projects/weather/lib/python3.9/site-packages/multiprocess/pool.py", line 350, in _check_running
    raise ValueError("Pool not running")
ValueError: Pool not running