clarification on max_buffer_size vs max_queue_size

[xiankaing]

Are these two just the same thing but
max_queue_size is for async producer
and
max_buffer_size is for normal/sync producer?

[dasch]

The async producer in fact wraps a sync producer, so when producing async a message will first be placed in the queue (which is thread safe), then be picked up by a background thread and placed in the sync producer's buffer, and then flushed to Kafka at some point.