code: func (sc *DocumentsWriterStallControl) updateStalled(stalled bool) {
  	sc.Lock()
  	defer sc.Unlock()
  	sc.stalled = stalled
  	if stalled {
  		sc.wasStalled = true
  	}
  	sc.Signal()
  }
docs: /*
  Update the stalled flag status. This method will set the stalled flag
  to true iff the number of flushing DWPT is greater than the number of
  active DWPT. Otherwise it will reset the DWSC to healthy and release
  all threads waiting on waitIfStalled()
  */