e caused by a <code>weakCompareAndSet</code>, it does
 not necessarily see updates to any <em>other</em> variables that
 occurred before the <code>weakCompareAndSet</code>.  This may be
 acceptable when, for example, updating performance statistics, but
 rarely otherwise.

 <p>The <code><a href="../../../../../reference/java/util/concurrent/atomic/AtomicMarkableReference.html">AtomicMarkableReference</a></code>
 class associates a single boolean with a reference.  For example, this
 bit might be used inside