Consider the case where `max_in_flight == 1` and you were connected to 5 producers and one of the connections disconnected.  Let's also assume that the connection that was lost had the RDY of 1.

It does not appear that `balance()` will ever be called to trigger redistribution.  The consumer will be deadlocked until some other connection event happens.

This can be resolved in a few ways but I put this comment here because I think this periodic callback should be setup at instantiation time, ensuring that it is always executed.  The function can exit early if it has no work to do.

In `pynsq` we alo set a flag when a connection closes that had RDY > 0 that would trigger redistribution on the next "balance callback".