// No other thread is coordinating. Become the coordinator!
        else -> {
          coordinatorWaiting = true
          coordinatorWakeUpAt = now + minDelayNanos
          try {
            backend.coordinatorWait(this@TaskRunner, minDelayNanos)
          } catch (_: InterruptedException) {
            // Will cause all tasks to exit unless more are scheduled!
            cancelAll()
          } finally {

 * [advanceUntil]. These functions don't return until the task threads are all idle.
 *
 * Task threads release their execution privilege in these ways:
 *
 *  * By yielding in [TaskRunner.Backend.coordinatorWait].
 *  * By yielding in [BlockingQueue.poll].
 *  * By completing.
 */
class TaskFaker : Closeable {
  @Suppress("NOTHING_TO_INLINE")
  internal inline fun Any.assertThreadHoldsLock() {