if (labelTypePatternList == null) {
            synchronized (this) {
                if (labelTypePatternList == null) {
                    buildLabelTypePatternList(ComponentUtil.getComponent(LabelTypeService.class).getLabelTypeList());
                }
            }
        }

        if (labelTypePatternList.isEmpty()) {
            return Collections.emptySet();

        WebConfig webConfig = new WebConfig();
        ComponentUtil.getCrawlingConfigHelper().store("test", webConfig);
        setValueToObject(ComponentUtil.getLabelTypeHelper(), "labelTypePatternList", new ArrayList<LabelTypePattern>());

        System.gc();
        long current = MemoryUtil.getUsedMemory();
        for (int i = 0; i < 10000; i++) {
            if (i % 1000 == 0) {