Effective network slicing requires an infrastructure/network provider to deal with the uncertain demand and real-time dynamics of network resource requests. Another challenge is the combinatorial optimization of numerous resources, e.g., radio, computing, and storage. This article develops an optimal and fast real-time resource slicing framework that maximizes the long-term return of the network provider while taking into account the uncertainty of resource demand from tenants. Specifically, we first propose a novel system model which enables the network provider to effectively slice various types of resources to different classes of users under separate virtual slices. We then capture the real-time arrival of slice requests by a semi-Markov decision process. To obtain the optimal resource allocation policy under the dynamics of slicing requests, e.g., uncertain service time and resource demands, a Q-learning algorithm is often adopted in the literature. However, such an algorithm is notorious for its slow convergence, especially for problems with large state/action spaces. This makes Q-learning practically inapplicable to our case in which multiple resources are simultaneously optimized. To tackle it, we propose a novel network slicing approach with an advanced deep learning architecture, called deep dueling that attains the optimal average reward much faster than the conventional Q-learning algorithm. This property is especially desirable to cope with real-time resource requests and the dynamic demands of users. Extensive simulations show that the proposed framework yields up to 40% higher long-term average return while being few thousand times faster, compared with state of the art network slicing approaches. {Hoang.Dinh, Diep.Nguyen, and Eryk.Dutkiewicz}@uts.edu.au. and development. In order to enhance operators' products for vertical enterprises and provide service customization for emerging massive connections, as well as to give more control to enterprises and mobile virtual network operators, the concept of network slicing has been recently introduced to allow the independent usage of a part of network resources by a group of mobile terminals with special requirements.Network slicing was introduced by Next Generation Mobile Networks Alliance [2], and it has quickly received a lot of attention from both academia and industry. In general, network slicing is a novel virtualization paradigm that enables multiple logical networks, i.e., slices, to be created according to specific technical or commercial demands and simultaneously run on top of the physical network infrastructure. The core idea of the network slicing is using software-defined networking (SDN) and network functions virtualization (NFV) technologies for virtualizing the physical infrastructure and controlling network operations. In particular, SDN provides a separation between the network control and data planes, improving the flexibility of network function management and efficiency of data transfer. Meanwhile, NFV allows various network functio...