[hinkley]

Seems that the trick would be detecting if there is a queue building up and dispatching multiple events per lock if so. Double buffering is a common enough solution here. The reader gets one buffer to write to and the writer gets another, and when the read buffer is drained the write buffer is swapped.

For low traffic messages you need only send one message at a time, but if the receiver slows down the sender can avoid resorting to back pressure until the buffer is more than half full.