BUG: asyncio: memory leak in socket.poll

What pyzmq version?

25.1.0

What libzmq version?

4.3.4

Python version (and how it was installed)

3.11.4

OS

openSUSE 15.4

What happened?

Futures returned by async socket.poll are not removed from socket._recv_futures if the future is cancelled before the event arrives. This is similar to #968, just in socket rather than poller. The sample code counts up to 10.

Code to reproduce bug

import zmq
import zmq.asyncio
import asyncio

context = zmq.asyncio.Context()

async def leak():
    socket = context.socket(zmq.REP)
    socket.bind('inproc://#1')
    for _ in range(10):
        future = socket.poll(flags=zmq.POLLIN)
        future.cancel()
        await asyncio.sleep(0)  # allow callbacks to run
        print(len(socket._recv_futures))

asyncio.run(leak())

Traceback, if applicable

No response

More info