httpclient 单例模式会出现并发问题？

如题，代码如下：

    private HttpClientUtils() {
        if (client == null) {
            client = HttpClients.createDefault();
        }
    }

    public static HttpClientUtils getInstance() {
        if (ins == null) {
            synchronized (HttpClientUtils.class) {
                if (ins == null) {
                    ins = new HttpClientUtils();
                }
            }
        }
        return ins;
    }

http://blog.csdn.net/gongzi2311/article/details/43705607