Threads are a natural means of dealing with concurrency. In Systems II, basic thread primitives were introduced and alternatives were presented with simple "echo" server.

• sequential - no concurrency
• concurrency forking separate processes
• concurrency using threads
• multiplexing clients with the select system call
• concurrency using a pool of threads, etc.

The first program assignment revisits (reviews) multithreading in the context of a simple data base. Complications beyond the creating multiple threads - one for each client - are managing concurrent threads that can both query and modify the database. the