Our os::random() implementation only returns 31 bits, the 32nd bit is always set to 0 because of our choice of implementation:

   * next_rand = (16807*seed) mod (2**31-1)

If one wants to use it to choose between true/false, one might be tempted to use:

  if (os::random() > 0) {
  } else {
  }

but that will not work, since the returned value will always be positive.

We should rename os::random() to os::random31bits(), and/or provide os::random_interval(int range)

Adding a comment would also be useful.

Hopefully, this would help to use this API correctly.