code: public void setSessionBackupAsync( final boolean sessionBackupAsync ) {
          final boolean oldSessionBackupAsync = _sessionBackupAsync;
          _sessionBackupAsync = sessionBackupAsync;
          if ( ( oldSessionBackupAsync != sessionBackupAsync ) && _manager.isInitialized() ) {
              _log.info( "SessionBackupAsync was changed to " + sessionBackupAsync + ", creating new BackupSessionService with new configuration." );
              _backupSessionService = new BackupSessionService( _transcoderService, _sessionBackupAsync, _sessionBackupTimeout,
                      _backupThreadCount, _storage, _memcachedNodesManager, _statistics );
          }
      }
docs: Specifies if the session shall be stored asynchronously in memcached as
  {@link StorageClient#set(String, int, byte[])} supports it. If this is
  false, the timeout set via {@link #setSessionBackupTimeout(int)} is
  evaluated. If this is <code>true</code>, the {@link #setBackupThreadCount(int)}
  is evaluated.
  <p>
  By default this property is set to <code>true</code> - the session
  backup is performed asynchronously.
  </p>
  
  @param sessionBackupAsync
  the sessionBackupAsync to set