title: in multi threaded code does System.nanoTime() produces small inaccuracy
body: <p>in multi-threaded code does System.nanoTime() produces small inaccuracy  whenever the threads are rescheduled?
   and if yes does this error accumulates and is this also true in single-threaded code?</p>
  
  <p>for example when threads start executing it get the time using System.nanoTime() at the beginning and then just before exiting from thread block it records the time using same System.nanoTime()</p>