New serverStatus metrics for the added queueing. New server parameters to configure max concurrency size for queues.

Description of Linked Ticket

Summary

Implement a single queue at the data node ingress layer. This queue will be backed by a max concurrency ticketing system.

Motivation

Queuing at the data node ingress layer allows the customer to avoid data-bearing nodes receiving a number of operations that would induce overload symptoms. Backing the queue with a max concurrency ticketing system allows two levels of observability and constraint, having insight into both how many operations are currently running, and how many operations would like to begin running.

Documentation

Product Description
Scope
Technical Design
Docs Update