I'm coming from a parallel computation, distributed systems background by education, and have relatively strong foundations in infrastructural concurrent/parallel libraries and products that I've built and maintained over the years both on the JVM and .Net.
Recently, I've dedicated more and more time building and deploying real concurrent projects with Ruby using JRuby, as opposed to developing with Ruby (MRI) with concurrency the way it is (process-level and GIL thread-level). I'd like to share some of that with you.
Feel free to bug me on twitter:
This may come as a lengthy information-packed read. You can put the blame on me for this one because I wanted to increase the value for the reader as much as possible and pack something that could have been a lengthy book, into a single highly concentrated no-bullshit article.
As an experiment, I also put most of the example code in a repository including the source of this article. Please feel free to fork and apply contributions of any kind, I'll gladly accept pull requests.
Github repo: https://github.com/jondot/pcwr
Concurrency is Awesome!
Remember those old 8-bit games you used to play as a child?. In a hindsight - you know its awesome, but if you're a gamer or just a casual gamer, and you're forced to play it today, the graphics will feel bad.
This is because it’s a detail thing; just like childhood computer games, as time passes, it seems like your brain doesn't care (or forgets) the proper details.
So given that one is an MRI Ruby developer, her mindset would be that concurrency just works, and it is easy and awesome. But you might be right guessing that due to the level of cynicism going around here - it isn't the end of it.
The MRI Ruby GIL is gracefully keeping some details away from you: yes things are running in parallel with the help of properly built I/O libraries (for example: historically, the MySQL gem was initially not doing it properly, which meant your thread would block on I/O), but surely, code isn't running in parallel. It's just like what your brain did when it covered up for those horrific 8-bit graphics that you were sure are still awesome.Read more →