(druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:579:in `load': connection closed (DRb::DRbConnError)
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:641:in `recv_reply'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:941:in `recv_reply'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1254:in `send_message'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1142:in `block (2 levels) in method_missing'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1229:in `open'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1141:in `block in method_missing'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1160:in `with_friend'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1140:in `method_missing'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/invokemethod.rb:11:in `block_yield'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/invokemethod.rb:18:in `block in perform_with_block'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/invokemethod.rb:15:in `each'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/invokemethod.rb:15:in `each_with_index'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/invokemethod.rb:15:in `perform_with_block'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1582:in `perform'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1668:in `block (2 levels) in main_loop'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1664:in `loop'
	from (druby://localhost:9999) /Users/user1/.rubies/ruby-2.4.0/lib/ruby/2.4.0/drb/drb.rb:1664:in `block in main_loop'
	from drb_client_test.rb:4:in `<main>'