Python/Mongo - Generating dummy data

Question

I wrote below piece of code generating dummy data loaded to MongoDB.

2 issues :

1.customer class has subscriber class so it nested with one level customer--> subsciber. I think i'm not doing right:

self.subscriber = Subscriber().returnJson()

it does working , but what if need to add another class under subscriber? it will become messy.

2.Peroformance - very bad:

10 documents:

real    0m20.371s
user    0m2.691s
sys     0m0.736s

for 1000 documents - very bad:

real    5m8.299s
user    1m40.819s
sys     0m44.380s

The generating of documents is the bottleneck - not the actual load.

Surely multiprocessing didn't work well , as performance is really bad. second ,I collect all document in a list (see mongo_doc[]) and at the end use insert_many i think it right , but it doesn't show meaningful improvement compare to insert_one.

Would appreciate any help

from faker import Faker
import json

from multiprocessing.pool import ThreadPool as Pool

import concurrent.futures
import random


from motor.motor_asyncio import AsyncIOMotorClient
from config.config import DB, CONF,trace_request,redis_client


pool_size = 10
mongo_docs = []



customer_type_options = ['Individual', 'Organization']
customer_status_options = ['Active', 'Cancelled','Suspened','Collection']



class Subscriber():

    def __init__(self):
        fake = Faker()
        self.subscriber_no= random.randint(10000000, 99999999)
    def returnJson(self):
        return dict (subscriber_no= self.subscriber_no)

class Customer():

    def __init__(self):
        fake = Faker()
        self.customer_no = random.randint(10000000, 99999999)
        self.customer_type = random.choice(customer_type_options)
        self.customer_status = random.choice(customer_status_options)
        self.address = fake.address()
        self.subscriber = Subscriber().returnJson()

    def returnJson(self):
        return {'customer_no': self.customer_no,
                'customer_type': self.customer_type,
                'customer_status': self.customer_status,
                'address': self.address,
            'subscriber': self.subscriber
        }

class ComplexEncoder(json.JSONEncoder):
    def default(self, obj):
        if hasattr(obj,'returnJson'):
            return obj.returnJson()
        else:
            return json.JSONEncoder.default(self, obj)

def LoadOToMongo(Customer):
    mongo_docs.append(Customer.returnJson()) 
    
    

if __name__ == "__main__":
    no_of_input = 2
    pool = Pool(pool_size)
    jobs =[]
    for i in range(0, no_of_input):
       customer = Customer()
       pool.apply_async(LoadOToMongo, (customer,))
    
    pool.close()
    pool.join()
#bulk insert 
    DB.customer.insert_many(mongo_docs)
    
```