backoff.py

class ExponentialBackoff:
    def __init__(self, base=1, integral=False):
        self._base = base

        self._exp = 0
        self._max = 10
        self._reset_time = base * 2 ** 11
        self._last_invocation = time.monotonic()

        r = random.Random()
        r.seed()

        self._randfunc = r.randrange if integral else r.uniform

    def delay(self):
        invocation = time.monotonic()
        interval = invocation - self._last_invocation
        self._last_invocation = invocation

        if interval > self._reset_time:
            self._exp = 0

        self._exp = min(self._exp + 1, self._max)
        return self._randfunc(0, self._base * 2 ** self._exp)

example.py

backoff = ExponentialBackoff()
while not self.is_closed():
    try:
        await func()
    except (
        aiohttp.ClientError,
        asyncio.TimeoutError,
        websockets.InvalidHandshake,
        websockets.WebSocketProtocolError
    ) as exc:
        if not reconnect:
            await self.close()
            raise

        if self.is_closed():
            return

        retry = backoff.delay()
        log.exception("Attempting a reconnect in %.2fs", retry)
        await asyncio.sleep(retry, loop=self.loop)