Returns the task queue used by this executor. Access to the
task queue is intended primarily for debugging and monitoring.
This queue may be in active use. Retrieving the task queue
does not prevent queued tasks from executing.
<p>Each element of this queue is a {@link ScheduledFuture}.
For tasks submitted via one of the {@code schedule} methods, the
element will be identical to the returned {@code ScheduledFuture}.
For tasks submitted using {@link #execute execute}, the element
will be a zero-delay {@code ScheduledFuture}.
<p>Iteration over this queue is <em>not</em> guaranteed to traverse
tasks in the order in which they will execute.
Returns the task queue used by this executor. Access to the task queue is intended primarily for debugging and monitoring. This queue may be in active use. Retrieving the task queue does not prevent queued tasks from executing.
<p>Each element of this queue is a {@link ScheduledFuture}. For tasks submitted via one of the {@code schedule} methods, the element will be identical to the returned {@code ScheduledFuture}. For tasks submitted using {@link #execute execute}, the element will be a zero-delay {@code ScheduledFuture}.
<p>Iteration over this queue is <em>not</em> guaranteed to traverse tasks in the order in which they will execute.
@return the task queue