Under the hood: MySQL Pool Scanner (MPS)

“Facebook has one of the largest MySQL database clusters in the world. This cluster comprises many thousands of servers across multiple data centers on two continents.

Operating a cluster of this size with a small team is achieved by automating nearly everything a conventional MySQL Database Administrator (DBA) might do so that the cluster can almost run itself. One of the core components of this automation is a system we call MPS, short for “MySQL Pool Scanner.”

MPS is a sophisticated state machine written mostly in Python. It replaces a DBA for many routine tasks and enables us to perform maintenance operations in bulk with little or no human intervention…”

https://www.facebook.com/notes/facebook-engineering/under-the-hood-mysql-pool-scanner-mps/10151750529723920