How to refer to the current thread

Question

When I want to refer to the current thread within the environment of a thread, several strategies seem to work:

• t = Thread.new{p t}
• Thread.new{|t| p t}
• Thread.new{p Thread.current}
• Thread.new{p self}

Are they all equivalent? Is there a reason to choose one over the others in a specific context?

Answer 1

self will only work if you call it directly within the block passed to Thread.new, not if you call it from inside a method on another class which runs on that thread. If you use the Thread.new { |t| p t} approach, you will have to pass t around if you want to use it inside other methods which are run on that thread. But Thread.current works no matter where you call it from.

I would use Thread.current, because it makes it obvious what you're doing to anybody reading the code. Some readers might not know that if the Thread.new block takes a parameter, the new thread will be passed in to that parameter. self might not be 100% clear either. But any reader should immediately be able to understand what Thread.current means.

Answer 2

The short answer is: Thread.current is most common approach to get current thread