Dual-pivot and beyond: The potential of multiway partitioning in quicksort
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Dr. Sebastian Wild studied computer science at
Technische Universität Kaiserslautern on a scholarship byStudienstiftung des deutschen Volkes and graduated in 2012 with a Master of Science. After that he did his Ph. D. aswissenschaftlicher Mitarbeiter (employed doctoral candidate with teaching duties) in the research group of Prof. Dr. Markus Nebel. His findings in the field of analysis of algorithms soon led to publications and international collaborations, including aBest Paper Award [18 ] at the European Symposium on Algorithms 2012. Sebastian was continually involved in teaching. During his studies he was a student tutor and during his Ph. D. years, he was responsible for organizing tutorials and involved in the development of new courses. Sebastian is married and father of three children.
Abstract
Since 2011 the Java runtime library uses a Quicksort variant with two pivot elements. For reasons that remained unclear for years it is faster than the previous Quicksort implementation by more than 10 %; this is not only surprising because the previous code was highly-tuned and is used in many programming libraries, but also since earlier theoretical investigations suggested that using several pivots in Quicksort is not helpful.
In my dissertation I proved by a comprehensive mathematical analysis of all sensible Quicksort partitioning variants that (a) indeed there is hardly any advantage to be gained from multiway partitioning in terms of the number of comparisons (and more generally in terms of CPU costs), but (b) multiway partitioning does significantly reduce the amount of data to be moved between CPU and main memory. Moreover, this more efficient use of the memory hierarchy is not achieved by any of the other well-known optimizations of Quicksort, but only through the use of several pivots.
About the author
Dr. Sebastian Wild studied computer science at Technische Universität Kaiserslautern on a scholarship by Studienstiftung des deutschen Volkes and graduated in 2012 with a Master of Science. After that he did his Ph. D. as wissenschaftlicher Mitarbeiter (employed doctoral candidate with teaching duties) in the research group of Prof. Dr. Markus Nebel. His findings in the field of analysis of algorithms soon led to publications and international collaborations, including a Best Paper Award [18] at the European Symposium on Algorithms 2012. Sebastian was continually involved in teaching. During his studies he was a student tutor and during his Ph. D. years, he was responsible for organizing tutorials and involved in the development of new courses. Sebastian is married and father of three children.
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Articles in the same Issue
- Frontmatter
- Editorial
- Industry 4.0
- Thematic Issue: Industry 4.0
- Digital twin technology – An approach for Industrie 4.0 vertical and horizontal lifecycle integration
- Business process management for Industry 4.0 – Three application cases in the DFKI-Smart-Lego-Factory
- Blockchain in Industrie 4.0: Beyond cryptocurrency
- Flexible IT platform for synchronizing energy demands with volatile markets
- Efficient and fast monitoring and disruption management for a pressure diecast system
- Distinguished Dissertations
- Dual-pivot and beyond: The potential of multiway partitioning in quicksort
