[{"conference":{"name":"SPAA: Symposium on Parallelism in Algorithms and Architectures","location":"Virtual, Online","start_date":"2021-07-06","end_date":"2021-07-08"},"doi":"10.1145/3409964.3461810","department":[{"_id":"DaAl"}],"abstract":[{"lang":"eng","text":"Dynamic Connectivity is a fundamental algorithmic graph problem, motivated by a wide range of applications to social and communication networks and used as a building block in various other algorithms, such as the bi-connectivity and the dynamic minimal spanning tree problems. In brief, we wish to maintain the connected components of the graph under dynamic edge insertions and deletions. In the sequential case, the problem has been well-studied from both theoretical and practical perspectives. However, much less is known about efficient concurrent solutions to this problem. This is the gap we address in this paper. We start from one of the classic data structures used to solve this problem, the Euler Tour Tree. Our first contribution is a non-blocking single-writer implementation of it. We leverage this data structure to obtain the first truly concurrent generalization of dynamic connectivity, which preserves the time complexity of its sequential counterpart, but is also scalable in practice. To achieve this, we rely on three main techniques. The first is to ensure that connectivity queries, which usually dominate real-world workloads, are non-blocking. The second non-trivial technique expands the above idea by making all queries that do not change the connectivity structure non-blocking. The third ingredient is applying fine-grained locking for updating the connected components, which allows operations on disjoint components to occur in parallel. We evaluate the resulting algorithm on various workloads, executing on both real and synthetic graphs. The results show the efficiency of each of the proposed optimizations; the most efficient variant improves the performance of a coarse-grained based implementation on realistic scenarios up to 6x on average and up to 30x when connectivity queries dominate."}],"scopus_import":"1","publication_identifier":{"isbn":["9781450380706"]},"_id":"10853","article_processing_charge":"No","publication_status":"published","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/2105.08098"}],"author":[{"full_name":"Fedorov, Alexander","first_name":"Alexander","last_name":"Fedorov"},{"first_name":"Nikita","last_name":"Koval","full_name":"Koval, Nikita"},{"first_name":"Dan-Adrian","orcid":"0000-0003-3650-940X","last_name":"Alistarh","id":"4A899BFC-F248-11E8-B48F-1D18A9856A87","full_name":"Alistarh, Dan-Adrian"}],"date_created":"2022-03-18T08:21:47Z","language":[{"iso":"eng"}],"date_published":"2021-07-01T00:00:00Z","date_updated":"2022-03-18T08:45:46Z","year":"2021","month":"07","arxiv":1,"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","publication":"Proceedings of the 33rd ACM Symposium on Parallelism in Algorithms and Architectures","type":"conference","publisher":"Association for Computing Machinery","quality_controlled":"1","oa_version":"Preprint","day":"01","external_id":{"arxiv":["2105.08098"]},"oa":1,"title":"A scalable concurrent algorithm for dynamic connectivity","status":"public","page":"208-220","citation":{"ista":"Fedorov A, Koval N, Alistarh D-A. 2021. A scalable concurrent algorithm for dynamic connectivity. Proceedings of the 33rd ACM Symposium on Parallelism in Algorithms and Architectures. SPAA: Symposium on Parallelism in Algorithms and Architectures, 208–220.","chicago":"Fedorov, Alexander, Nikita Koval, and Dan-Adrian Alistarh. “A Scalable Concurrent Algorithm for Dynamic Connectivity.” In <i>Proceedings of the 33rd ACM Symposium on Parallelism in Algorithms and Architectures</i>, 208–20. Association for Computing Machinery, 2021. <a href=\"https://doi.org/10.1145/3409964.3461810\">https://doi.org/10.1145/3409964.3461810</a>.","apa":"Fedorov, A., Koval, N., &#38; Alistarh, D.-A. (2021). A scalable concurrent algorithm for dynamic connectivity. In <i>Proceedings of the 33rd ACM Symposium on Parallelism in Algorithms and Architectures</i> (pp. 208–220). Virtual, Online: Association for Computing Machinery. <a href=\"https://doi.org/10.1145/3409964.3461810\">https://doi.org/10.1145/3409964.3461810</a>","ama":"Fedorov A, Koval N, Alistarh D-A. A scalable concurrent algorithm for dynamic connectivity. In: <i>Proceedings of the 33rd ACM Symposium on Parallelism in Algorithms and Architectures</i>. Association for Computing Machinery; 2021:208-220. doi:<a href=\"https://doi.org/10.1145/3409964.3461810\">10.1145/3409964.3461810</a>","ieee":"A. Fedorov, N. Koval, and D.-A. Alistarh, “A scalable concurrent algorithm for dynamic connectivity,” in <i>Proceedings of the 33rd ACM Symposium on Parallelism in Algorithms and Architectures</i>, Virtual, Online, 2021, pp. 208–220.","short":"A. Fedorov, N. Koval, D.-A. Alistarh, in:, Proceedings of the 33rd ACM Symposium on Parallelism in Algorithms and Architectures, Association for Computing Machinery, 2021, pp. 208–220.","mla":"Fedorov, Alexander, et al. “A Scalable Concurrent Algorithm for Dynamic Connectivity.” <i>Proceedings of the 33rd ACM Symposium on Parallelism in Algorithms and Architectures</i>, Association for Computing Machinery, 2021, pp. 208–20, doi:<a href=\"https://doi.org/10.1145/3409964.3461810\">10.1145/3409964.3461810</a>."}},{"scopus_import":"1","ec_funded":1,"abstract":[{"text":"We introduce a new graph problem, the token dropping game, and we show how to solve it efficiently in a distributed setting. We use the token dropping game as a tool to design an efficient distributed algorithm for stable orientations and more generally for locally optimal semi-matchings. The prior work by Czygrinow et al. (DISC 2012) finds a stable orientation in O(Δ^5) rounds in graphs of maximum degree Δ, while we improve it to O(Δ^4) and also prove a lower bound of Ω(Δ). For the more general problem of locally optimal semi-matchings, the prior upper bound is O(S^5) and our new algorithm runs in O(C · S^4) rounds, which is an improvement for C = o(S); here C and S are the maximum degrees of customers and servers, respectively.","lang":"eng"}],"doi":"10.1145/3409964.3461785","department":[{"_id":"DaAl"}],"conference":{"end_date":"2021-07-08","start_date":"2021-07-06","name":"SPAA: Symposium on Parallelism in Algorithms and Architectures ","location":" Virtual Event, United States"},"publication_status":"published","publication_identifier":{"isbn":["9781450380706"]},"related_material":{"record":[{"status":"public","relation":"earlier_version","id":"15074"}]},"_id":"9678","article_processing_charge":"No","date_created":"2021-07-18T22:01:22Z","author":[{"last_name":"Brandt","first_name":"Sebastian","full_name":"Brandt, Sebastian"},{"first_name":"Barbara","last_name":"Keller","full_name":"Keller, Barbara"},{"full_name":"Rybicki, Joel","last_name":"Rybicki","orcid":"0000-0002-6432-6646","id":"334EFD2E-F248-11E8-B48F-1D18A9856A87","first_name":"Joel"},{"last_name":"Suomela","first_name":"Jukka","full_name":"Suomela, Jukka"},{"full_name":"Uitto, Jara","first_name":"Jara","last_name":"Uitto"}],"main_file_link":[{"url":"https://arxiv.org/abs/2005.07761","open_access":"1"}],"project":[{"name":"Coordination in constrained and natural distributed systems","grant_number":"840605","_id":"26A5D39A-B435-11E9-9278-68D0E5697425","call_identifier":"H2020"}],"acknowledgement":"We thank Orr Fischer, Juho Hirvonen, and Tuomo Lempiäinen for valuable discussions. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 840605.","arxiv":1,"user_id":"D865714E-FA4E-11E9-B85B-F5C5E5697425","year":"2021","month":"07","date_published":"2021-07-06T00:00:00Z","language":[{"iso":"eng"}],"date_updated":"2025-04-14T07:50:55Z","type":"conference","publication":"Annual ACM Symposium on Parallelism in Algorithms and Architectures","title":"Efficient load-balancing through distributed token dropping","external_id":{"arxiv":["2005.07761"]},"day":"06","oa":1,"quality_controlled":"1","oa_version":"Preprint","citation":{"apa":"Brandt, S., Keller, B., Rybicki, J., Suomela, J., &#38; Uitto, J. (2021). Efficient load-balancing through distributed token dropping. In <i>Annual ACM Symposium on Parallelism in Algorithms and Architectures</i> (pp. 129–139).  Virtual Event, United States. <a href=\"https://doi.org/10.1145/3409964.3461785\">https://doi.org/10.1145/3409964.3461785</a>","ama":"Brandt S, Keller B, Rybicki J, Suomela J, Uitto J. Efficient load-balancing through distributed token dropping. In: <i>Annual ACM Symposium on Parallelism in Algorithms and Architectures</i>. ; 2021:129-139. doi:<a href=\"https://doi.org/10.1145/3409964.3461785\">10.1145/3409964.3461785</a>","chicago":"Brandt, Sebastian, Barbara Keller, Joel Rybicki, Jukka Suomela, and Jara Uitto. “Efficient Load-Balancing through Distributed Token Dropping.” In <i>Annual ACM Symposium on Parallelism in Algorithms and Architectures</i>, 129–39, 2021. <a href=\"https://doi.org/10.1145/3409964.3461785\">https://doi.org/10.1145/3409964.3461785</a>.","ista":"Brandt S, Keller B, Rybicki J, Suomela J, Uitto J. 2021. Efficient load-balancing through distributed token dropping. Annual ACM Symposium on Parallelism in Algorithms and Architectures. SPAA: Symposium on Parallelism in Algorithms and Architectures , 129–139.","short":"S. Brandt, B. Keller, J. Rybicki, J. Suomela, J. Uitto, in:, Annual ACM Symposium on Parallelism in Algorithms and Architectures, 2021, pp. 129–139.","mla":"Brandt, Sebastian, et al. “Efficient Load-Balancing through Distributed Token Dropping.” <i>Annual ACM Symposium on Parallelism in Algorithms and Architectures</i>, 2021, pp. 129–39, doi:<a href=\"https://doi.org/10.1145/3409964.3461785\">10.1145/3409964.3461785</a>.","ieee":"S. Brandt, B. Keller, J. Rybicki, J. Suomela, and J. Uitto, “Efficient load-balancing through distributed token dropping,” in <i>Annual ACM Symposium on Parallelism in Algorithms and Architectures</i>,  Virtual Event, United States, 2021, pp. 129–139."},"page":"129-139","status":"public"}]