Ruby/Threads/abort on exception

Thread.abort_on_exception = true 
threads = [] 
4.times do |number| 
    threads << Thread.new(number) do |i| 
        raise "Boom!" if i == 2 
        print "#{i}\n" 
    end 
end 
threads.each {|t| t.join }

t1 = Thread.new do
  puts "Hello"
  sleep 2
  raise "some exception"
  puts "Goodbye"
end
t1.abort_on_exception = true
t2 = Thread.new { sleep 100 }
sleep 2
puts "The End"