This paper presents a novel technique for synthesizing large textures of high quality in real time. By analyzing the texture periodicity, patches in an optimized size are generated to well represent the variation of exemplar features. Then, during synthesizing, the paper first distributes patches on the output texture with a vacant region left between any pair of neighboring patches in every row and every column, where a vacant region is also in the same size as a patch. Thereafter, patches are selected to fill the vacant regions in the output texture. Obviously, both patch distributing and vacant region filling can be executed in parallel. To accelerate, for each patch, the paper constructs a set of matching patches that can be efficiently merged with the corresponding patch. The computation of patch selection for vacant regions, therefore, can be simplified into set intersection. Moreover, patch distribution and set intersection are performed on a CPU while patch stitching are executed on a GPU, to take advantage of both CPU and GPU. Experimental results show that the presented method is able to generate a high-quality texture in 1024*1024 pixels at over 45 frames per second, which is hard to achieve by existing techniques.