Best resource to learn parallel/concurrent programming?

If you are familiar with a language that either supports the Actor Model[0] natively, or has a library[1] that offers support for the model, I recommend trying to write concurrent applications using that.

I struggled with concurrency quite a bit until I stumbled upon the Akka framework for Scala. I was already familiar with Scala, so that made it easy to learn in terms of what I already knew. The Actor Model itself is a very simple concurrency model, and I think understanding that makes it easier to understand other concurrency paradigms.

[0] https://en.wikipedia.org/wiki/Actor_model

[1] https://en.wikipedia.org/wiki/Actor_model#Actor_libraries_an...

Also check out the references / further reading / external links on that wiki page for actual resources.

To truly grok what you're getting into, I'd recommend watching Kevlin Henney's talk about concurrency[1]. The key quote

  "when you introduce concurrency into a non-concurrent environment what you do is you change the laws of physics of your program, you change the nature of time"

[1] https://www.youtube.com/watch?v=Hi6ICEVVRiw