private boolean shouldCallExpireBatch() {
      if (testHook_forceExpirationCount > 0) {
        return false;
      }
      if (forceBatchExpiration) {
        return true;
      }
      if (testHook_forceBatchExpireCall != null) {
        return true;
      }
      return expiredTombstones.size() >= EXPIRED_TOMBSTONE_LIMIT;
    }
Returns true if keys needs to be tracked for clients registering interests on PR.
geode-core/src/main/java/org/apache/geode/internal/cache/TombstoneService.java