synchronized private void startWorker(final Writer out){
  if (f != null && !f.isDone())   return;
  Runnable r=new AsyncWriterRunnable(out);
  f=e.submit(r,out);
}

synchronized private void startWorker ( final Writer out ) { if ( f != null && ! f . isDone ( ) ) return ; Runnable r = new AsyncWriterRunnable ( out ) ; f = e . submit ( r , out ) ; }
starts a new worker thread
