def f(x):
    set_time = 60
    timeout = time.time() + 60*float(set_time)  # X minutes from now
    print(timeout)
    while True:
        if time.time() > timeout:
            print("Time to ack!")
            print(time.time())
            break
        x * x

def create_load(percent_load):
    processes = psutil.cpu_count()
    to_use = int(processes * (percent_load/100))
    print ('utilizing %d cores\n' % to_use)
    pool = Pool(to_use)
    pool.map(f, range(to_use))

def receive_messages_with_flow_control() -> None:
    """Receives messages from a pull subscription with flow control."""
    from concurrent.futures import TimeoutError
    from google.cloud import pubsub_v1

    subscriber = pubsub_v1.SubscriberClient()
    subscription_path = subscriber.subscription_path(project_id, subscription_id)

    def callback(message: pubsub_v1.subscriber.message.Message) -> None:
        print(f"Received {message.data!r} at {time.time()}.")
        create_load(50)
        message.ack()

    # Limit the subscriber to only have ten outstanding messages at a time.
    flow_control = pubsub_v1.types.FlowControl(max_messages=1)

    streaming_pull_future = subscriber.subscribe(
        subscription_path, callback=callback, flow_control=flow_control
    )

    # Wrap subscriber in a 'with' block to automatically call close() when done.
    with subscriber:
        try:
            # When `timeout` is not set, result() will block indefinitely,
            # unless an exception is encountered first.
            streaming_pull_future.result()
        except TimeoutError:
            streaming_pull_future.cancel()  # Trigger the shutdown.
            streaming_pull_future.result()  # Block until the shutdown is complete.

google.api_core.exceptions.InvalidArgument: 400 Some acknowledgement ids in the request were invalid. This could be because the acknowledgement ids have expired or the acknowledgement ids were malformed. [reason: "EXACTLY_ONCE_ACKID_FAILURE"
domain: "pubsub.googleapis.com"
metadata {
  value: "PERMANENT_FAILURE_INVALID_ACK_ID"
}