Can you tell if a Ruby gem is really thread-safe or not? And how do you fix a seemingly thread-safety issue that can be something else entirely?

We had no idea. So we asked Nate Berkopec to help us. Nate is an expert in Ruby performance.

The verdict: nuking all shared global mutable state in your Ruby code is a bad idea if you don’t know what you’re doing!

Listen to this episode to learn:

• How and why faker-ruby became thread-unsafe, especially for Puma users
• Questions to ask yourself when trying to debug thread-safety issues
• Shared global mutable state is not always the villain, and is not the source of all thread-safety issues
• Nate’s “watch-out” list of things that can cause undesired behavior when running multi-threaded Ruby applications: Constants, Class Variables, and Rack Middleware.

Episode Link