private volatile boolean generating;

    private Thread thumbnailQueueThread;

    protected int thumbnailPathCacheSize = 10;

    protected String imageExtention = "png";

    protected int splitSize = 10;

    protected int thumbnailTaskQueueSize = 10000;

    protected int thumbnailTaskBulkSize = 100;

    protected long thumbnailTaskQueueTimeout = 10 * 1000L;