multithreading - Inconsistent output with Ruby threads and puts -

i writing program perform number of checks , output results via puts. want speed process using threads. however, output includes inconsistent new lines.

how can cleanup output?

ex.

> (1..99).each_with_object([]) {|i, threads| threads << thread.new {sleep(rand 2) && puts(i)} }.each(&:join) 7 202535 36605562 7882 8959958 2826  29 433941 445258  69728063 777975    85496  22  14 24    3850    9712 9892   47  40  71 84  94 49        1 2 152187131627234218194531535759 305417 34647448 735111 66684676 838137 6133 679093 917099 3       56  32   10  6                88    86  65 

updated tin man's comment

use print/printf or puts , provide new-line char \n explicitly (since puts may write new-line separately rest , other threads may jumping in).

(1..99).each_with_object([]) {|i, threads| threads << thread.new {sleep(rand 2) && print("#{i}\n") } }.each(&:join)