You are building a system that records student marks in an in-memory data structure. It is important that the system works efficiently and correctly for multiple concurrent users. There are 2 classes of operation: recording a mark for a student and generating a report of a students marks. Whenever an operation takes place an audit record is kept of that operation. This is done by appending a record (user, date-time, operation performed) to a global string that records all of the operations that have been performed on the database. You can ignore practical issues e.g. of data persistence or memory use and can assume that reading/writing a mark is an atomic operation.

Explain what issues could arise from having multiple concurrent users of this system. You should propose a solution to these potential problems and provide an argument for why you have chosen this solution rather than other alternatives. Explain what the implications are of implementing your proposal.