gistfile1.rb

class Semaphore
  def self.get(name, options = {})
    # Create a new Redis connection specifically for the semaphore.
    # Treat a semaphore as stale if it's too old. We have to assume that processing was interrupted, so that we can try the same files again.
    Redis::Semaphore.new(name.to_sym,
      :redis => Aperture.redis,
      stale_client_timeout: options[:stale_client_timeout].try(:to_i) || 1.hour,
    )
  end
end

# Run this on server 1 in rails console
sema = Semaphore.get("my_semaphore_key")
sema.lock # Or you can do sema.lock do sleep(20) end

# Then run this on server 2 in rails console
sema = Semaphore.get("my_semaphore_key")
[2] pry(main)> sema.locked?
=> false

# It will always be false, even though it should return saying it is locked