In this paper, we study the relationship between two fundammental problem in Robotics namely, leader election problem and pattern formation problem. In particular, we prove that both problems are equivalent for n≥4 in a fully asynchronous model, called CORDA, provided the robots share the same chirality.
{"title":"Brief announcement: leader election vs pattern formation","authors":"Yoann Dieudonné, F. Petit, V. Villain","doi":"10.1145/1835698.1835793","DOIUrl":"https://doi.org/10.1145/1835698.1835793","url":null,"abstract":"In this paper, we study the relationship between two fundammental problem in Robotics namely, leader election problem and pattern formation problem. In particular, we prove that both problems are equivalent for n≥4 in a fully asynchronous model, called CORDA, provided the robots share the same chirality.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131229065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Session details: Regular papers","authors":"M. Aguilera","doi":"10.1145/3258220","DOIUrl":"https://doi.org/10.1145/3258220","url":null,"abstract":"","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123901051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We give a graph decomposition technique that creates entirely independent subproblems for graph problems such as coloring and dominating sets that can be solved without synchronization on a distributed memory system. For coloring, evaluation shows a performance gain of a factor 3 to 5 at the price of using more colors.
{"title":"Brief announcement: efficient graph algorithms without synchronization","authors":"Johannes Schneider, Roger Wattenhofer","doi":"10.1145/1835698.1835769","DOIUrl":"https://doi.org/10.1145/1835698.1835769","url":null,"abstract":"We give a graph decomposition technique that creates entirely independent subproblems for graph problems such as coloring and dominating sets that can be solved without synchronization on a distributed memory system. For coloring, evaluation shows a performance gain of a factor 3 to 5 at the price of using more colors.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117132116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we address the problem of content placement in peer-to-peer systems, with the objective of maximizing the utilization of peers' uplink bandwidth resources. We consider system performance under a many-user asymptotic. We identify optimal content placement strategies in a particular scenario of limited content catalogue, casting the problem into the framework of loss networks. We then turn to an alternative "large catalogue" scaling where the catalogue size grows with the peer population. Relating the system performance to properties of a specific random graph model, we establish a content placement strategy which again maximizes system performance, provided storage space per peer grows unboundedly, although arbitrarily slowly, with system size.
{"title":"Brief announcement: adaptive content placement for peer-to-peer video-on-demand systems","authors":"Bo Tan, L. Massoulié","doi":"10.1145/1835698.1835771","DOIUrl":"https://doi.org/10.1145/1835698.1835771","url":null,"abstract":"In this paper, we address the problem of content placement in peer-to-peer systems, with the objective of maximizing the utilization of peers' uplink bandwidth resources. We consider system performance under a many-user asymptotic. We identify optimal content placement strategies in a particular scenario of limited content catalogue, casting the problem into the framework of loss networks. We then turn to an alternative \"large catalogue\" scaling where the catalogue size grows with the peer population. Relating the system performance to properties of a specific random graph model, we establish a content placement strategy which again maximizes system performance, provided storage space per peer grows unboundedly, although arbitrarily slowly, with system size.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117254288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We quantify the effect of Bayesian ignorance by comparing the social cost obtained in a Bayesian game by agents with local views to the expected social cost of agents having global views. Both benevolent agents, whose goal is to minimize the social cost, and selfish agents, aiming at minimizing their own individual costs, are considered. When dealing with selfish agents, we consider both best and worst equilibria outcomes. While our model is general, most of our results concern the setting of network cost sharing (NCS) games. We provide tight asymptotic results on the effect of Bayesian ignorance in directed and undirected NCS games with benevolent and selfish agents. Among our findings we expose the counter-intuitive phenomenon that "gnorance is bliss": Bayesian ignorance may substantially improve the social cost of selfish agents. We also prove that public random bits can replace the knowledge of the common prior in attempt to bound the effect of Bayesian ignorance in settings with benevolent agents. Together, our work initiates the study of the effects of local vs. global views on the social cost of agents in Bayesian contexts.
{"title":"Bayesian ignorance","authors":"N. Alon, Y. Emek, M. Feldman, Moshe Tennenholtz","doi":"10.1145/1835698.1835785","DOIUrl":"https://doi.org/10.1145/1835698.1835785","url":null,"abstract":"We quantify the effect of Bayesian ignorance by comparing the social cost obtained in a Bayesian game by agents with local views to the expected social cost of agents having global views. Both benevolent agents, whose goal is to minimize the social cost, and selfish agents, aiming at minimizing their own individual costs, are considered. When dealing with selfish agents, we consider both best and worst equilibria outcomes. While our model is general, most of our results concern the setting of network cost sharing (NCS) games. We provide tight asymptotic results on the effect of Bayesian ignorance in directed and undirected NCS games with benevolent and selfish agents. Among our findings we expose the counter-intuitive phenomenon that \"gnorance is bliss\": Bayesian ignorance may substantially improve the social cost of selfish agents. We also prove that public random bits can replace the knowledge of the common prior in attempt to bound the effect of Bayesian ignorance in settings with benevolent agents. Together, our work initiates the study of the effects of local vs. global views on the social cost of agents in Bayesian contexts.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115130286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wait-freedom and obstruction-freedom have received a lot of attention in the literature. These are symmetric progress conditions in the sense that they consider all processes as being "equal". Wait-freedom has allowed to rank the synchronization power of objects in presence of process failures, while (the weaker) obstruction-freedom allows for simpler and more efficient object implementations. This paper introduces the notion of asymmetric progress conditions. Given an object O in a shared memory system of n processes, we say that O satisfies (y,x)-liveness if O can be accessed by a subset of y ≤ n processes only, and it guarantees wait-freedom for x processes and obstruction-freedom for the remaining y-x processes. Notice that, (n,n)-liveness is wait-freedom while (n,0)-liveness is obstruction-freedom. The main contributions are: (1) an impossibility result showing that there is no (n,1)-live consensus object even if one can use underlying (n-1,n-1)-live consensus objects and registers, (2) an (n,x)-liveness hierarchy for 0 ≤ x ≤ n, and (3) an impossibility result showing that there is no consensus object for n processes that is obstruction-free with respect to all processes and fault-free with respect to a single process even if one can use underlying (n-1,n-1)-live consensus objects and registers (a process is fault-free if it always terminates when all the processes participate and there are no faults). (4) An implementation based on (x,x)-live objects that constructs a consensus object for any number of n ≤ x processes which satisfies an asymmetric group-based progress condition.
{"title":"On asymmetric progress conditions","authors":"Damien Imbs, M. Raynal, G. Taubenfeld","doi":"10.1145/1835698.1835709","DOIUrl":"https://doi.org/10.1145/1835698.1835709","url":null,"abstract":"Wait-freedom and obstruction-freedom have received a lot of attention in the literature. These are symmetric progress conditions in the sense that they consider all processes as being \"equal\". Wait-freedom has allowed to rank the synchronization power of objects in presence of process failures, while (the weaker) obstruction-freedom allows for simpler and more efficient object implementations. This paper introduces the notion of asymmetric progress conditions. Given an object O in a shared memory system of n processes, we say that O satisfies (y,x)-liveness if O can be accessed by a subset of y ≤ n processes only, and it guarantees wait-freedom for x processes and obstruction-freedom for the remaining y-x processes. Notice that, (n,n)-liveness is wait-freedom while (n,0)-liveness is obstruction-freedom. The main contributions are: (1) an impossibility result showing that there is no (n,1)-live consensus object even if one can use underlying (n-1,n-1)-live consensus objects and registers, (2) an (n,x)-liveness hierarchy for 0 ≤ x ≤ n, and (3) an impossibility result showing that there is no consensus object for n processes that is obstruction-free with respect to all processes and fault-free with respect to a single process even if one can use underlying (n-1,n-1)-live consensus objects and registers (a process is fault-free if it always terminates when all the processes participate and there are no faults). (4) An implementation based on (x,x)-live objects that constructs a consensus object for any number of n ≤ x processes which satisfies an asymmetric group-based progress condition.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129427993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We show how to partition data structures representable by directed acyclic graphs, i.e. rooted trees, to allow for efficient complex operations, which lie beyond inserts, deletes and finds. The approach potentially improves the performance of any operation modifying more than one element of the data structure. It covers common data structures implementable via linked lists or trees such as sets and maps. We demonstrate its simplicity and its effectiveness using a concurrent sorted linked list. We achieve a speedup of up to 250% even for small divisions.
{"title":"Brief announcement: tree decomposition for faster concurrent data structures","authors":"Johannes Schneider, Roger Wattenhofer","doi":"10.1145/1835698.1835768","DOIUrl":"https://doi.org/10.1145/1835698.1835768","url":null,"abstract":"We show how to partition data structures representable by directed acyclic graphs, i.e. rooted trees, to allow for efficient complex operations, which lie beyond inserts, deletes and finds. The approach potentially improves the performance of any operation modifying more than one element of the data structure. It covers common data structures implementable via linked lists or trees such as sets and maps. We demonstrate its simplicity and its effectiveness using a concurrent sorted linked list. We achieve a speedup of up to 250% even for small divisions.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130185995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Large-scale hosting infrastructures require automatic system anomaly management to achieve continuous system operation. In this paper, we present a novel adaptive runtime anomaly prediction system, called ALERT, to achieve robust hosting infrastructures. In contrast to traditional anomaly detection schemes, ALERT aims at raising advance anomaly alerts to achieve just-in-time anomaly prevention. We propose a novel context-aware anomaly prediction scheme to improve prediction accuracy in dynamic hosting infrastructures. We have implemented the ALERT system and deployed it on several production hosting infrastructures such as IBM System S stream processing cluster and PlanetLab. Our experiments show that ALERT can achieve high prediction accuracy for a range of system anomalies and impose low overhead to the hosting infrastructure.
大型托管基础设施需要对系统异常进行自动化管理，以实现系统的连续运行。在本文中，我们提出了一种新的自适应运行时异常预测系统，称为ALERT，以实现健壮的托管基础设施。与传统的异常检测方案相比，ALERT旨在提前提出异常警报，以实现及时的异常预防。为了提高动态托管基础设施的预测精度，提出了一种新的上下文感知异常预测方案。我们已经实现了ALERT系统，并将其部署在几个生产托管基础设施上，如IBM system S流处理集群和PlanetLab。我们的实验表明，ALERT可以对一系列系统异常实现较高的预测精度，并且对托管基础设施施加较低的开销。
{"title":"Adaptive system anomaly prediction for large-scale hosting infrastructures","authors":"Yongmin Tan, Xiaohui Gu, Haixun Wang","doi":"10.1145/1835698.1835741","DOIUrl":"https://doi.org/10.1145/1835698.1835741","url":null,"abstract":"Large-scale hosting infrastructures require automatic system anomaly management to achieve continuous system operation. In this paper, we present a novel adaptive runtime anomaly prediction system, called ALERT, to achieve robust hosting infrastructures. In contrast to traditional anomaly detection schemes, ALERT aims at raising advance anomaly alerts to achieve just-in-time anomaly prevention. We propose a novel context-aware anomaly prediction scheme to improve prediction accuracy in dynamic hosting infrastructures. We have implemented the ALERT system and deployed it on several production hosting infrastructures such as IBM System S stream processing cluster and PlanetLab. Our experiments show that ALERT can achieve high prediction accuracy for a range of system anomalies and impose low overhead to the hosting infrastructure.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121233122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An effective way to reduce the number of aborts in software transactional memory (STM) is to keep multiple versions of transactional objects. In this paper, we study inherent properties of STMs that use multiple versions to guarantee successful commits of all read-only transactions. We first show that these STMs cannot be disjoint-access parallel. We then consider the problem of garbage collecting old object versions, and show that no STM can be optimal in the number of previous versions kept. Moreover, we show that garbage collecting useless versions is impossible in STMs that implement invisible reads. Finally, we present an STM algorithm using visible reads that efficiently garbage collects useless object versions.
{"title":"On maintaining multiple versions in STM","authors":"D. Perelman, Rui Fan, I. Keidar","doi":"10.1145/1835698.1835704","DOIUrl":"https://doi.org/10.1145/1835698.1835704","url":null,"abstract":"An effective way to reduce the number of aborts in software transactional memory (STM) is to keep multiple versions of transactional objects. In this paper, we study inherent properties of STMs that use multiple versions to guarantee successful commits of all read-only transactions. We first show that these STMs cannot be disjoint-access parallel. We then consider the problem of garbage collecting old object versions, and show that no STM can be optimal in the number of previous versions kept. Moreover, we show that garbage collecting useless versions is impossible in STMs that implement invisible reads. Finally, we present an STM algorithm using visible reads that efficiently garbage collects useless object versions.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115827882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Session details: Regular papers","authors":"C. Cachin","doi":"10.1145/3258214","DOIUrl":"https://doi.org/10.1145/3258214","url":null,"abstract":"","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126781546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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