4.8.1 Introduction

In this exercise you will be introduced to the problems of concurrency control for multiple read and writes to a server. You will learn about the problem of testing of interleaved actions from multiple clients when reading state and then potentially modifying the state based on the previously read state. In particular, you will learn about

• Lost updates

You will then learn how to structure the reads and writes using transactions, and how locks can be used to control concurrency.

Finally, you will have the chance to investigate how to implement a lock manager.