问题
I'm trying to implement a service which consumes a google pubsub subscription at its own pace. By that, I mean I need fine control on when I need to consume messages i.e get a batch of messages, pause for a while, do not get more than X messages...
Using google client libraries I did not find a way to do it as the MessageReceiver is running in its own thread and I don't have any control on what exactly happens.
Basically, being able to consume messages in a synchronous way should solve my issue.
Do you know how I can use the google client libs synchronously ? Or is there another way in the API I missed ?
回答1:
You might try using setFlowControlSettings when you build your subscriber. In particular, you can use setMaxOutstandingElementCount or setMaxOutstandingRequestBytes to limit the messages sent to your MessageReceiver. When you have enough messages outstanding, i.e., messages for which you have not called Ack() or Nack(), to exceed these limits, then your MessageReceiver will not be called until messages have been acked or nacked.
来源：https://stackoverflow.com/questions/44812934/google-pubsub-flow-control