*/
        void onRegistrationFailed(WitnessRegistration registration, Exception error);

        /**
         * Called when a witness registration expires.
         *
         * @param registration the expired registration
         */
        void onRegistrationExpired(WitnessRegistration registration);
    }

    /**
     * Creates a new witness client.
     *

    /**
     * The token parameter.
     */
    public static final String TOKEN = "token";

    /**
     * The expires parameter.
     */
    public static final String EXPIRES = "expires";

    /**
     * The expired time parameter.
     */
    public static final String EXPIRED_TIME = "expiredTime";

        } else {
            crawlingInfo.setName(Constants.CRAWLING_INFO_SYSTEM_NAME);
        }
        if (dayForCleanup >= 0) {
            final long expires = getExpiredTime(dayForCleanup);
            crawlingInfo.setExpiredTime(expires);
            documentExpires = expires;
        }
        try {
            getCrawlingInfoService().store(crawlingInfo);
        } catch (final Exception e) {

Depois, ele 🤖 pega a primeira tarefa para finalizar (vamos dizer, nosso "arquivo lento" 📝) e continua o que tem que fazer com ela.

Esse "esperar por algo" normalmente se refere a operações <abbr title="Input and Output – Entrada e Saída">I/O</abbr> que são relativamente "lentas" (comparadas à velocidade do processador e da memória RAM), como esperar por:

* dados do cliente para serem enviados através da rede

                    return true;
                }

                final Date expires = DocumentUtil.getValue(document, fessConfig.getIndexFieldExpires(), Date.class);
                if (expires != null && expires.getTime() < systemHelper.getCurrentTimeAsLong()) {
                    final Object idValue = document.get(fessConfig.getIndexFieldId());

        // After update, should not be expired with long timeout
        assertFalse(registration.isExpired(60000));

        // Verify heartbeat was actually updated
        assertTrue(registration.getLastHeartbeat() > initialTime);
    }

    @Test
    void testExpiration() throws InterruptedException {
        // Registration should not be expired initially with long timeout

  /** If a cookie incorrectly defines multiple 'Expires' attributes, the last one defined wins.  */
  @Test fun lastExpiresAtWins() {
    assertThat(
      parseCookie(
        0L,
        url,
        "a=b; " +
          "Expires=Thu, 01 Jan 1970 00:00:02 GMT; " +
          "Expires=Thu, 01 Jan 1970 00:00:04 GMT; " +
          "Expires=Thu, 01 Jan 1970 00:00:01 GMT; " +
          "Expires=Thu, 01 Jan 1970 00:00:03 GMT",

      if (responseCaching.maxAgeSeconds != -1) {
        return SECONDS.toMillis(responseCaching.maxAgeSeconds.toLong())
      }

      val expires = this.expires
      if (expires != null) {
        val servedMillis = servedDate?.time ?: receivedResponseMillis
        val delta = expires.time - servedMillis
        return if (delta > 0L) delta else 0L
      }

    /** Parameter key for controlling deletion of old documents */
    private static final String DELETE_OLD_DOCS = "delete_old_docs";

    /** Parameter key for controlling retention of expired documents */
    private static final String KEEP_EXPIRES_DOCS = "keep_expires_docs";

    /**
     * Interval in milliseconds between crawler thread executions.

                DirectoryCacheScope.IMMEDIATE_CHILDREN);

        // Make the cache entry expired
        DirectoryCacheEntry entry = directoryLeaseManager.getCacheEntry(directoryPath);
        entry.setMaxAge(1); // 1ms to expire immediately
        try {
            Thread.sleep(10);
        } catch (InterruptedException e) {
            // Ignore
        }