Spring cloud stream and backpressure using PubSubReactiveFactory

Question

I am trying to implement a flow control similar to https://cloud.google.com/pubsub/docs/pull#flow_control using spring cloud stream reactive client.

@Bean
ApplicationRunner reactiveSubscriber(PubSubReactiveFactory reactiveFactory, PubSubMessageConverter converter) {
  return (args) -> {
    reactiveFactory.poll("orders-subscription", 250L)
      // Convert a JSON payload into an object
      .map(msg -> converter.fromPubSubMessage(msg.getPubsubMessage(), Order.class))
      .doOnNext(order -> proccessOrder(order))
      // Mannually acknowledge the message
      .doOnNext(AcknowledgeablePubsubMessage::ack);
      .subscribe();
  };
}

It seems that back-pressure is not possible to limit number of data flowing through the system. Since the processing can last for few second I am afraid to cause some memory problems with high number of incoming message (millions of incoming message per day).

What I would like to achieve is a constant processing of 100 messages in the flux. Anyone had success implement it ? Maybe reactive rabbitmq ?

Answer 1

resolved using spring amqp and prefetch count.