RuntimeError: Task attached to a different loop

Question

Hi I'm using AsyncIOMotorClient for asynchronous db calls to mongoDb. Below is my code.

xyz.py
async def insertMany(self,collection_name,documents_to_insert):
    try:
        collection=self.database[collection_name]
        document_inserted = await collection.insert_many(documents_to_insert)
        return document_inserted
    except Exception:
        raise

def insertManyFn(self,collection_name,documents_to_insert):
    try:
        loop=asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        loop1=asyncio.get_event_loop()
        inserted_documents_count = loop1.run_until_complete(self.insertMany(collection_name, documents_to_insert))
        if inserted_documents_count==len(documents_to_insert):
            document_to_insert={Config.DB_JOB_COLUMN:Job.job_id,Config.DB_JOB_RESULT_COLUMN:Config.DB_JOB_RESULT_SUCCESS}
            loop1.run_until_complete(self.insertOne(Config.DB_JOB_COLLECTION, document_to_insert))
    except Exception:
        raise

xyz1.py
t=Timer(10,xyz.insertManyFn,\
                (collection_name,documents_to_insert))
t.start()   

While running this I'm getting an exception

RuntimeError: Task <Task pending coro=<xyz.insertMany() running at <my workspace location>/xyz.py:144> cb=[_run_until_complete_cb() at /usr/lib64/python3.5/asyncio/base_events.py:164]> got Future <Future pending cb=[_chain_future.<locals>._call_check_cancel() at /usr/lib64/python3.5/asyncio/futures.py:431]> attached to a different loop

In the above program insertManyFn will be called after 10sec and do the insert operation. But when it make the first call to insertMany I'm getting an exception.

Answer 1

I still want my MotorClient to be at the top level of the module, so this is what I do: I patch MotorClient.get_io_loop to always return the current loop.

import asyncio
import motor.core

from motor.motor_asyncio import (
    AsyncIOMotorClient as MotorClient,
)

# MongoDB client
client = MotorClient('mongodb://localhost:27017/test')
client.get_io_loop = asyncio.get_running_loop

# The current database ("test")
db = client.get_default_database()


# async context
async def main():
    posts = db.posts
    await posts.insert_one({'title': 'great success!')


# Run main()
asyncio.run(main())

Answer 2

According to the documentation, AsyncIOMotorClient should be passed an ioloop if you don't use the default one. Try creating the client after you create your event loop:

loop=asyncio.new_event_loop()
asyncio.set_event_loop(loop)
client = AsyncIOMotorClient(io_loop=loop)