* Using Object#wait() or Condition#await() has the problem that
  it can only be interrupted by Thread#interrupt() if it can acquire
  the monitor back. Otherwise, it stays stuck and in the case
  we are trying to get to a guest-language safepoint, deadlocks.
  The problem comes from the fact that the monitor must be hold while
  invoking the safepoint as we need to prevent another thread to notify() while
  we are interrupted and not in wait(). Since the monitor can be held
  during the safepoint, then interrupts sent by the safepoint are not unblocking
  threads waiting on the same condition with wait(), as they would need to acquire
  the lock that only one of the thread that got unblocked holds.
* The logic in Ruby is clearer and relies on Mutex#sleep and Thread#wakeup,
  which are simpler primitives and easier to implement.