Parallel merge sort with double merging

Sorting is one of the fundamental problems in computer science. With the proliferation of multi core processors, parallel algorithms for sorting have become very important. In this study, we propose a new parallel merge sort algorithm in which two threads perform the merge operation simultaneously. We have implemented the new merge sort algorithm in Java. We compared the results of the new algorithm with the parallel merge sort implemented in Java library. The results showed that the new algorithm provides between %20-%30 percent speed increase in a quad core system when sorting 10M to 50M double numbers.