title: Java code's CPU usage changing
body: <p>I ran into this observation when I was trying to give a rough estimate of my code's runtime: The CPU usage stayed at around 10% for the first part of the code, which involved traversing 2 strings and tossing things into a hashset. When the code reached the second part (2 nested for loops, plus a gigantic array allocation), the CPU usage skyrocketed to 50%. </p>
  
  <p>I don't think I did anything related to multithreading. Also if I slightly modify the first part (something really simple like adding another for loop), the CPU usage varies a lot too. Why is this happening? A bit curious about who's utilizing the CPU consumption. </p>