neurons firing from a keyboard

I was discussing the power of Goroutines a few days ago with a fellow co-worker. Naturally, the topic of “doing things at the same time in fancy ways” came up. In code, this is usually expressed by the async or await keywords depending on your language of choice. I told him that I really liked how Goroutines abstracts much of the grunt work in sharing state across multiple threads. As nicely as he possibly could, he responded with:

You know nothing! Goroutines don’t fork threads!

This sounded ludicrous to me. I (mistakenly) thought that concurrency == parallelism because doing things “concurrently” usually means doing them at the same time simultaneously, i.e. what is typically described as being run in parallel. Nobody ever says “I made a grilled cheese sandwich in parallel to waiting for x.” So I argued how concurrency is all about multithreading while he argued that concurrency is all about context switching. This small, but friendly, argument invited a few co-workers surrounding us, and much ado about event pumps were made.