Towards Ultra-scale Exact Optimization Using Chapel

International audienceTree-based search algorithms applied to combinatorial optimization problems are highly irregular and timeconsuming when it comes to solving big instances. Due to their parallel nature, algorithms of this class have been revisited for different architectures over the years, and these parallelization efforts have always been guided by the performance objective setting aside productivity. However, dealing with scalability implicitly induces the heterogeneity issue, which means that different programming models/languages, runtimes and libraries need to be employed together for efficiently exploiting all levels of parallelism of large-scale systems. As a consequence, efforts towards productivity are crucial for harnessing the future generation of supercomputers. In this document, we present our efforts towards productivity-aware ultra-scale tree search using the Chapel language. Four topics are covered in this document: the design and implementation of tree-search using Chapel, improving intra-node efficiency, the use of GPUs and future perspectives