test.rb

#!ruby

trap("INT") do
  puts "in int"

  10.times do
    masters = Thread.list.select { |t| t[:master] }
    if masters.count > 0
      masters.first[:terminate] = true
      masters.first.join
      break
    else
      puts "retrying main thread kill in one second"
      sleep 1
    end
  end

  # put exit here -- not here so we can test races
end

10.times do
  Process.kill "INT", Process.pid

  Thread.new do
    Thread.current[:master] = true
    loop do
      if Thread.current[:terminate]
        puts "exiting"
        break
      else
        sleep 1
      end
    end
  end

  sleep 1
end

p Thread.list.count