Schedules this {@code SwingWorker} for execution on a
worker thread. There are a number of
workerthreads available. In the event all
worker threads are busy handling other {@code SwingWorkers} this{@code SwingWorker} is placed in a waiting queue.
Note: {@code SwingWorker} is only designed to be executed once. Executing a {@code SwingWorker} more than oncewill not result in invoking the {@code doInBackground} method twice.