Concurrency vs Parallelism

Concurrency vs Parallelism

Concurrency and Parallelism are often confused to refer to the ability of a system to run multiple distinct programs at the same time. Though the two terms are somewhat related they mean very different things. To clarify the concept, we'll borrow a juggler from a circus to use as an analogy. Consider the juggler to be a machine and the balls he juggles as processes.

Serial Execution

When programs are serially executed, they are scheduled one at a time on the CPU. Once a task gets completed, the next one gets a chance to run. Each task is run from beginning to end without interruption. The analogy for serial execution is a circus juggler who can only juggle one ball at a time. Definitely not very entertaining!

Concurrency

A concurrent program is one that can be decomposed into constituent parts and each part can be executed out of order or in partial order without affecting the final outcome. A system capable of running several distinct programs or more than one independent unit of the same ...