Chapter 9, Challenges of Testing Concurrent Code

1. Concurrency refers to a program’s ability to execute more than one task, with interruptions and without any ordering guarantees. Parallelism refers to a program’s ability to execute more than one task, simultaneously and without interruptions. The OS (or even in silico implementations such as hyperthreading) may give the illusion of parallelism through pre-emptive multitasking. However, in order for parallelism to be truly simultaneous, multiple computational resources are required.
2. Channels support three operations. The send operation writes information to the channel, while the receive operation reads information from the channel. The close operation signals to all receivers that no more values will be sent through it. Once closed, channels can never be reopened. For unbuffered channels, send and receive operations are synchronous and will only complete once both sender and receiver are available. On closed channels...