Programming Concurrency on the JVM

Is it Concurrency or Parallelism?

There’s no clear distinction between these two terms in the industry, and the number of answers we’ll hear is close to the number of people we ask for an explanation (and don’t ask them concurrently…or should I say in parallel?).

Let’s not debate the distinction here. We may run programs on a single core with multiple threads and later deploy them on multiple cores with multiple threads. When our code runs within a single JVM, both these deployment options have some common concerns—how do we create and manage threads, how do we ensure integrity of data, how do we deal with locks and synchronization, and are our threads crossing the memory barrier at the appropriate times...?

Whether we call it concurrent or ...