Connections not closing when async tasks are cancelled

[Landon]

Description

When a task is cancelled while an aiosqlite.Connection object is connecting, the sqlite connection is never closed and is left hanging. Additionally the aiosqlite.Connection threads don't get shut down.

Details

• OS: Windows 10 Pro 10.0.19045
• Python version: 3.11.5
• aiosqlite version: 0.19.0
• Can you repro on 'main' branch? Yes
• Can you repro in a clean virtualenv? Yes

Repro code:

import asyncio

import aiosqlite


async def connect_to_db():
    async with aiosqlite.connect("test.db") as db:
        await db.execute("SELECT value FROM generate_series(0,1000000,1)")


async def main_loop():
    tasks = []

    for i in range(5):
        tasks.append(asyncio.create_task(connect_to_db()))
    print("Tasks started")

    await asyncio.sleep(0)
    print("Async tick")

    for task in tasks:
        task.cancel()
    print("Tasks cancelled")

    for task in tasks:
        try:
            await task
        except asyncio.CancelledError:
            continue

    # This was a debug helper to track open connections
    # from aiosqlite.core import print_connections_info
    # print_connections_info()

    await asyncio.sleep(5)
    print("Complete")


if __name__ == "__main__":
    asyncio.run(main_loop())

Expected behavior: File handles for test.db would be released as tasks were successfully cancelled.

Actual behavior: 5 file handles are kept indefinitely for test.db (can be verified with a program such as OpenedFilesView or keeping track of the sqlite connections). Additionally after the event loop stops, the script hangs.

[Landon]

I suspect there may be other problems when tasks are cancelled, but haven't figured out minimal test cases for them yet. My program was often getting into a state where a series of cancelled write tasks would eventually lock the database indefinitely.