I am using PubSubIO to read from Google PubSub as an unbounded source. I've noticed that the rate at which is receives messages is pretty slow compared to the rate at which messages are being pushed.
In the Google PubSub APIs, I can tweak a pull subscriber's settings using Subscriber.defaultBuilder().setExecutorProvider, where I can set the core pool size for the thread pool that will pull messages.
Is there any equivalent way of tuning the PubSubIO class as well? Or any other way of achieving a higher pull rate?