Question

Is it OK not to call Thread#join? In this case, I don’t care if the thread blows up – I just want Unicorn to keep processing.

class MyMiddleware
  def initialize(app)
    @app = app
  end

  def call(env)
    t = Thread.new { sleep 1 }
    t.join # is it ok if I skip this?
    @app.call env
  end
end

Will I get “zombie threads” or something like that?

Answer 1

It’s perfectly fine to not call join – in fact, join is often not needed at all with multithreaded code. You should only call join if you need to block until the new thread completes.

You won’t get a “zombie” thread. The new thread will run until completion, then clean itself up for you.