public void wakeup() {
    // if sendAndPoll is currently executing a timed poll on the blocking queue, we need to put WAKEUP_MARKER
    // to wake it up before a response comes
    try {
      queue.put(wakeupMarker);
    } catch (InterruptedException ie) {
      LOGGER.warn("Interrupted while waking up queue", ie);
    }
  }
Called to force a timed poll call to return before the timeout expires.
ambry-utils/src/main/java/com/github/ambry/utils/BatchBlockingQueue.java