Couchbase Write Queue when Streaming Data

We’re trying to develop a application that streams a large volume of data into k-v store in Couchbase. I’m trying to figure out:

  1. Is there a write queue and how to configure it?
  2. When calling upsert with SDK, what is the error code if the write queue is being filled up? - I want to implement a backoff strategy if we’re writing too fast.

I’ve been trying to look for these information in the documentation but cannot find any. Anyone can help?