How do they work on a CPU?

Understanding the differences outlined in the previous section between both concurrency and parallelism is essential, but it's also very important to understand more about the systems that your software will be running on. Having an appreciation of the different architecture styles as well as the low-level mechanics helps you make the most informed decisions in your software design.

Single-core CPUs

Single-core processors will only ever execute one thread at any given time as that is all they are capable of. However, in order to ensure that we don't see our applications hanging and being unresponsive, these processors rapidly switch between multiple threads of execution many thousands of...