[Python] How to Safely Share State Between Asyncio Tasks Running in a Separate Event Loop in a...

I'm working on a Python application where I run an asyncio event loop in a separate thread. I need to share state (e.g., a mutable dictionary) between asyncio tasks running on that loop and other threads in the application. I've tried using standard thread-safe primitives like threading.Lock, but I'm still encountering race conditions and occasional deadlocks.

For example, consider the following simplified code:

python

import asyncio
import threading

shared_state = {}

async def async_worker():
while True:
await asyncio.sleep(1)
# Update shared state
with lock:
shared_state['value'] = shared_state.get('value', 0) + 1
print("Async:", shared_state['value'])

def thread_worker(loop):
asyncio.set_event_loop(loop)
loop.run_forever()

lock = threading.Lock()
loop = asyncio.new_event_loop()
t = threading.Thread(target=thread_worker, args=(loop,))
t.start()

# Schedule async_worker in the separate event loop
asyncio.run_coroutine_threadsafe(async_worker(), loop)

# Meanwhile, update shared state from the main thread
def update_from_main():
for _ in range(5):
with lock:
shared_state['value'] = shared_state.get('value', 0) + 10
print("Main thread update:", shared_state['value'])
time.sleep(2)

import time
update_from_main()


The above code occasionally leads to inconsistent state or even hangs.

My questions are:

What is the best practice for sharing mutable state between asyncio tasks and synchronous threads? Should I rely solely on thread locks, or are there asyncio-specific constructs (or a different design pattern) that can help ensure thread safety? Is it better to confine all state mutations to the asyncio thread and communicate with other threads via message queues or similar patterns? Any insights or code examples that explain a robust solution would be greatly appreciated.

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