C H A P T E R 10 Concurrency HREADS allow multiple activities to proceed concurrently. Concurrent pro- gramming is harder than single-threaded programming, because more things can go wrong, and failures can be hard to reproduce. But you can't avoid concurrency. It is inherent in much of what we do, and a requirement if you are to obtain good perfor- mance from multicore processors, which are now commonplace. This chapter con- tains advice to help you write clear, correct, well-documented concurrent programs. T Item 66: Synchronize access to shared mutable data