You have now built your application and instituted various processes and mechanisms in anticipation of changes over its lifetime. An additional, but no less essential, process that you must have in place and carry out from time to time is monitoring and performance measurement. Any production application you build for real-world users and institutions must meet certain performance goals to be useful to its users, and by implication, the application's stakeholders. Therefore, understanding how your application performs and trying to improve its performance is a key maintenance task; any dereliction in this task may result in your application having a short shelf life.
The art (and science) of system performance measurement and analytics is a broad and extensive set of topics, and it is not our intention to cover these topics deeply or exhaustively in this book. To obtain such a coverage, the interested reader is encouraged to read other canonical texts on...