Threads creation with outer join (working)

threads_inner_join.rb

# THIS IS WRONG!
start_time = Time.new

10.times do
	t = Thread.new do |th|
		sec = rand(1..5)
		puts "Run for #{sec} s"
		sleep(sec)
		#th.join #first case
		puts "slept"
	end
	t.join #second case
end

puts "Execution time #{Time.new - start_time}"

#Execution in first case:
#ruby threads_inner_join.rb
#Run for 5 s
#Run for 5 s
#Run for 5 s
#Run for 3 s
#Run for 4 s
#Run for 3 s
#Run for 3 s
#Run for 4 s
#Run for 5 s
#Run for 3 s
#Execution time 40.026031. Это же очевидно, почему так - треды выполняются по очереди
#Execution in commented second case and uncommented first
#No output when ruby except Execution time 0.002 - not working
#In irb:
#threads_inner_join.rb(main):013:0* Run for 3 s
#Run for 1 s
#Run for 5 s
#Run for 3 s
#Run for 4 s
#Run for 1 s
#Run for 3 s
#Run for 3 s
#Run for 1 s
#Run for 5 s
#puts "Execution time #{Time.new - start_time}"
#Execution time 0.033001 - threads not working

threads_outer_join.rb

threads = []
start_time = Time.new

10.times do 
    threads << Thread.new do
    	st = rand(1..5)
	puts "Sleep for #{st}"
	sleep(st)
    end
end

threads.each { |t| t.join }
exec_time = Time.new - start_time
puts "Execution time #{exec_time}"

#Execution:ruby threads_outer_join.rb
#Sleep for 1
#Sleep for 5
#Sleep for 1
#Sleep for 3
#Sleep for 3
#Sleep for 2
#Sleep for 3
#Sleep for 1
#Sleep for 2
#Sleep for 5
#Execution time 5.016278