#vulnerable code 
                                @Override
    protected void pushWhenNoDuplicate(Request request, Task task) {
        if (!inited.get()) {
            init(task);
        }
        if(urls.contains(request.getUrl())) //已存在此URL 表示已抓取过 跳过
            return;
        queue.add(request);
        fileUrlWriter.println(request.getUrl());
    } 
                            #location 6 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @Override
    protected void pushWhenNoDuplicate(Request request, Task task) {
        if (!inited.get()) {
            init(task);
        }
        queue.add(request);
        fileUrlWriter.println(request.getUrl());
    }