Understanding traditional concurrency mechanisms

My recommendation is that, although old concurrency paradigms can be still used, you should not mix concurrency paradigms together, and you should use the newer approaches in new projects. However, let’s have a quick recap of older concurrency mechanisms.

Threads

A thread in concurrent programming is the smallest unit of a CPU execution that can run independently. Threads within the same process share the same memory space but execute independently. Each thread owns its own copy of registers, stack and program counter, but shares heap memory and file handles. Threads are one of the oldest and most traditional ways to achieve concurrency. A modern CPU can both switch the execution sequentially among several threads (concurrency) and can also process several threads in parallel on different CPU cores (parallelism).

It is nowadays uncommon to find a modern mobile device with less than four CPU cores. In a threaded model...