Now, when unschedulable Pods are updated, the scheduling queue checks with QueueingHint(s) whether the update may make the pods schedulable, and requeues them to activeQ/backoffQ **only when** at least one QueueingHint(s) return Queue. 
  
  Action required for custom scheduler plugin developers:

 * rate limit itself.
 *
 * <pre>{@code
 * class CrawlingService extends AbstractScheduledService {
 *   private Set<Uri> visited;
 *   private Queue<Uri> toCrawl;
 *   protected void startUp() throws Exception {
 *     toCrawl = readStartingUris();
 *   }
 *
 *   protected void runOneIteration() throws Exception {
 *     Uri uri = toCrawl.remove();

                "fess_user.user", //
                "configsync", //
        };
        final String[] crawlerIndices = { ".crawler.data", //
                ".crawler.filter", //
                ".crawler.queue", //
        };
        final SearchEngineClient client = ComponentUtil.getSearchEngineClient();
        for (final String index : configIndices) {
            final String oldIndex = "." + index;

	bucketNotificationBuf := `<NotificationConfiguration><QueueConfiguration><Event>s3:ObjectCreated:Put</Event><Filter><S3Key><FilterRule><Name>prefix</Name><Value>images/</Value></FilterRule></S3Key></Filter><Id>1</Id><Queue>arn:minio:sqs:us-east-1:444455556666:webhook</Queue></QueueConfiguration></NotificationConfiguration>`
	// generate a random bucket Name.
	bucketName := getRandomBucketName()
	// HTTP request to create the bucket.

    mostRecentRebuildFailed = false
  }

  /**
   * Returns a snapshot of the entry named [key], or null if it doesn't exist is not currently
   * readable. If a value is returned, it is moved to the head of the LRU queue.
   */
  @Synchronized
  @Throws(IOException::class)
  operator fun get(key: String): Snapshot? {
    initialize()

    checkNotClosed()
    validateKey(key)

,"toUpperCase","camelCase","string","acceptData","owner","Data","uid","defineProperty","configurable","set","data","prop","hasData","dataPriv","dataUser","rbrace","rmultiDash","dataAttr","JSON","parse","removeData","_data","_removeData","attrs","dequeue","startLength","hooks","_queueHooks","unshift","stop","setter","clearQueue","tmp","count","defer","pnum","source","rcssNum","cssExpand","isAttached","composed","getRootNode","isHiddenWithinTree","style","display","css","adjustCSS","valueParts","t...

- The scheduling queue didn't notice any extenders' failures, it could miss some cluster events,
  and it could end up Pods rejected by Extenders stuck in unschedulable pod pool in 5min in the worst-case scenario.

			}
			t.Log("Client Context canceled. err state:", err)
			clientCanceled <- time.Now()
		}(t)
		start := time.Now()
		if st.Requests != nil {
			defer close(st.Requests)
		}
		// Fill up queue.
		for sendReq {
			select {
			case st.Requests <- []byte("Hello"):
				time.Sleep(10 * time.Millisecond)
			default:
				sendReq = false
			}
		}
		cancel()
		<-serverCanceled

- The scheduling queue didn't notice any extenders' failures, it could miss some cluster events,
  and it could end up Pods rejected by Extenders stuck in unschedulable pod pool in 5min in the worst-case scenario.

,"toUpperCase","camelCase","string","acceptData","owner","Data","uid","defineProperty","configurable","set","data","prop","hasData","dataPriv","dataUser","rbrace","rmultiDash","dataAttr","JSON","parse","removeData","_data","_removeData","attrs","dequeue","startLength","hooks","_queueHooks","unshift","stop","setter","clearQueue","tmp","count","defer","pnum","source","rcssNum","cssExpand","isAttached","composed","getRootNode","isHiddenWithinTree","style","display","css","adjustCSS","valueParts","t...