We start by defining a pruning process involving sellers on one side and buyers on the other. The goal is to quickly select a subset of the sellers so that the products that these sellers bring to the market has small cost ratio, i.e., the ratio of the total cost of the selected sellers' products to amount that interested buyers are willing to pay. As modeled here, the pruning process can be used to speed up distributed implementations of greedy algorithms (e.g., for minimum dominating set, facility location, etc). We present a randomized instance of the pruning process that, for any positive k, runs in O(k) communication rounds with O(log N)-sized messages, yielding a cost ratio of O(Nc/k). Here N is the product of the number of sellers and number of buyers and c is a small constant. Using this O(k)-round pruning algorithm as the basis, we derive several simple, greedy, O(k)-round distributed approximation algorithms for MDS and facility location (both metric and non-metric versions). Our algorithms achieve optimal approximation ratios in polylogarithmic rounds and shave a "logarithmic factor" off the best, known, approximation factor, typically achieved using LP-rounding techniques.
{"title":"Rapid randomized pruning for fast greedy distributed algorithms","authors":"Saurav Pandit, S. Pemmaraju","doi":"10.1145/1835698.1835777","DOIUrl":"https://doi.org/10.1145/1835698.1835777","url":null,"abstract":"We start by defining a pruning process involving sellers on one side and buyers on the other. The goal is to quickly select a subset of the sellers so that the products that these sellers bring to the market has small cost ratio, i.e., the ratio of the total cost of the selected sellers' products to amount that interested buyers are willing to pay. As modeled here, the pruning process can be used to speed up distributed implementations of greedy algorithms (e.g., for minimum dominating set, facility location, etc). We present a randomized instance of the pruning process that, for any positive k, runs in O(k) communication rounds with O(log N)-sized messages, yielding a cost ratio of O(Nc/k). Here N is the product of the number of sellers and number of buyers and c is a small constant. Using this O(k)-round pruning algorithm as the basis, we derive several simple, greedy, O(k)-round distributed approximation algorithms for MDS and facility location (both metric and non-metric versions). Our algorithms achieve optimal approximation ratios in polylogarithmic rounds and shave a \"logarithmic factor\" off the best, known, approximation factor, typically achieved using LP-rounding techniques.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"58 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":"115359125","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}
Dmitriy Kuptsov, A. Gurtov, Óscar García-Morchón, Klaus Wehrle
Fair node and network operation is a key to ensure the correct system operation. The problem arises when some nodes become compromised or faulty endangering the overall system. This is especially challenging in sensor networks because they are often deployed in hostile environments and have to endure both passive and active attacks. Therefore, a node should only communicate with trusted nodes, while non-trusted nodes should be removed from the system to prevent them from further disrupting its normal operation. To address such threats, we introduce the Efficient Cooperative Security (ECoSec) - a distributed and adaptive protocol that allows a network to control the admission and revocation of nodes in a cooperative and democratic way during two voting rounds. Whereas the contributions of the protocol to the family of cooperative security protocols are two fold. First, it introduces the use of polynomial-based votes showing that its operation, and in general, operation of cooperative security protocols, can endure up to 33% of misbehaving nodes. Second, the protocol applies correlated keying material structures to verify the node admission and node revocation voting procedures reducing the overall communication overhead.
{"title":"Brief announcement: distributed trust management and revocation","authors":"Dmitriy Kuptsov, A. Gurtov, Óscar García-Morchón, Klaus Wehrle","doi":"10.1145/1835698.1835751","DOIUrl":"https://doi.org/10.1145/1835698.1835751","url":null,"abstract":"Fair node and network operation is a key to ensure the correct system operation. The problem arises when some nodes become compromised or faulty endangering the overall system. This is especially challenging in sensor networks because they are often deployed in hostile environments and have to endure both passive and active attacks. Therefore, a node should only communicate with trusted nodes, while non-trusted nodes should be removed from the system to prevent them from further disrupting its normal operation. To address such threats, we introduce the Efficient Cooperative Security (ECoSec) - a distributed and adaptive protocol that allows a network to control the admission and revocation of nodes in a cooperative and democratic way during two voting rounds. Whereas the contributions of the protocol to the family of cooperative security protocols are two fold. First, it introduces the use of polynomial-based votes showing that its operation, and in general, operation of cooperative security protocols, can endure up to 33% of misbehaving nodes. Second, the protocol applies correlated keying material structures to verify the node admission and node revocation voting procedures reducing the overall communication overhead.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"231 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":"115906697","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}
Dmitry Basin, K. Birman, I. Keidar, Ymir Vigfusson
Data centers, and particularly the massive ones that support cloud computing, e-commerce, social networking and other large-scale functionality, necessarily replicate data. Our basic premise is that since updates to replicated data can be thought of as reliable multicasts, data center multicast is a potentially important technology. Nonetheless, a series of recent keynote speeches at major conferences makes it clear that data center multicast is a troubled area [4, 2]. One might expect such technologies to use IP multicast hardware, but in fact this is rare. Only TCP is really trusted today (because it backs down when loss occurs), and indeed, TCP is the overwhelming favorite among data center transport protocols [3]. Using TCP to get reliable multicast with high throughput produces an implicit TCP overlay tree.
{"title":"Brief announcement: sources of instability in data center multicast","authors":"Dmitry Basin, K. Birman, I. Keidar, Ymir Vigfusson","doi":"10.1145/1835698.1835732","DOIUrl":"https://doi.org/10.1145/1835698.1835732","url":null,"abstract":"Data centers, and particularly the massive ones that support cloud computing, e-commerce, social networking and other large-scale functionality, necessarily replicate data. Our basic premise is that since updates to replicated data can be thought of as reliable multicasts, data center multicast is a potentially important technology. Nonetheless, a series of recent keynote speeches at major conferences makes it clear that data center multicast is a troubled area [4, 2]. One might expect such technologies to use IP multicast hardware, but in fact this is rare. Only TCP is really trusted today (because it backs down when loss occurs), and indeed, TCP is the overwhelming favorite among data center transport protocols [3]. Using TCP to get reliable multicast with high throughput produces an implicit TCP overlay tree.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"9 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":"114960224","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 consider the problem of efficiently constructing in a fully distributed manner multicast trees which are embedded into P2P overlays using virtual geometric node coordinates. We consider two objectives: to minimize the number of messages required for constructing a multicast tree by using the geometric properties of the P2P overlay, and to construct stable multicast trees when the lifetime durations of the peers are known.
{"title":"Brief announcement: decentralized construction of multicast trees embedded into P2P overlay networks based on virtual geometric coordinates","authors":"M. Andreica, Andrei Dragus, A. Sambotin, N. Tapus","doi":"10.1145/1835698.1835766","DOIUrl":"https://doi.org/10.1145/1835698.1835766","url":null,"abstract":"In this paper we consider the problem of efficiently constructing in a fully distributed manner multicast trees which are embedded into P2P overlays using virtual geometric node coordinates. We consider two objectives: to minimize the number of messages required for constructing a multicast tree by using the geometric properties of the P2P overlay, and to construct stable multicast trees when the lifetime durations of the peers are known.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"79 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":"125984167","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 present a single-version STM that satisfies a practical notion of permissiveness: it never aborts read-only transactions, and it only aborts an update transaction due to another conflicting update transaction, thereby avoiding many spurious aborts. It avoids unnecessary contention on the memory, being strictly disjoint-access parallel.
{"title":"Brief announcement: single-version permissive STM","authors":"H. Attiya, Eshcar Hillel","doi":"10.1145/1835698.1835712","DOIUrl":"https://doi.org/10.1145/1835698.1835712","url":null,"abstract":"We present a single-version STM that satisfies a practical notion of permissiveness: it never aborts read-only transactions, and it only aborts an update transaction due to another conflicting update transaction, thereby avoiding many spurious aborts. It avoids unnecessary contention on the memory, being strictly disjoint-access parallel.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"64 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":"121691624","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}
Multiparty computation (MPC) protocols among n parties secure against t active faults are known to exist if and only if t < n/2, when the channels are synchronous, and t < n/3, when the channels are asynchronous, respectively. In this work we analyze the gap between these bounds, and show that in the cryptographic setting (with setup), the sole reason for it is the distribution of inputs: given an oracle for input distribution, cryptographically-secure asynchronous MPC is possible with the very same condition as synchronous MPC, namely t < n/2. We do not know whether the gaps in other security models (perfect, statistical) have the same cause. We stress that all previous asynchronous MPC protocols inherently require t < n/3, even once inputs are distributed. In particular, all published asynchronous multiplication sub-protocols inherently require t < n/3 and cannot be used in our setting. Furthermore, we show that such an input-distribution oracle can be reduced to an oracle that allows each party to synchronously broadcast one single message. This means that when one single round of synchronous broadcast is available, then asynchronous MPC is possible at the same condition as synchronous MPC, namely t < n/2. If such a round cannot be used, then MPC (and even Byzantine agreement) requires t < n/3.
{"title":"On the theoretical gap between synchronous and asynchronous MPC protocols","authors":"Zuzana Beerliová-Trubíniová, M. Hirt, J. Nielsen","doi":"10.1145/1835698.1835746","DOIUrl":"https://doi.org/10.1145/1835698.1835746","url":null,"abstract":"Multiparty computation (MPC) protocols among n parties secure against t active faults are known to exist if and only if t < n/2, when the channels are synchronous, and t < n/3, when the channels are asynchronous, respectively. In this work we analyze the gap between these bounds, and show that in the cryptographic setting (with setup), the sole reason for it is the distribution of inputs: given an oracle for input distribution, cryptographically-secure asynchronous MPC is possible with the very same condition as synchronous MPC, namely t < n/2. We do not know whether the gaps in other security models (perfect, statistical) have the same cause. We stress that all previous asynchronous MPC protocols inherently require t < n/3, even once inputs are distributed. In particular, all published asynchronous multiplication sub-protocols inherently require t < n/3 and cannot be used in our setting. Furthermore, we show that such an input-distribution oracle can be reduced to an oracle that allows each party to synchronously broadcast one single message. This means that when one single round of synchronous broadcast is available, then asynchronous MPC is possible at the same condition as synchronous MPC, namely t < n/2. If such a round cannot be used, then MPC (and even Byzantine agreement) requires t < n/3.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"94 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":"122060005","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}
Mutual exclusion is a fundamental distributed coordination problem. Shared-memory mutual exclusion research focuses on local-spin algorithms and uses the remote memory references (RMRs) metric. A mutual exclusion algorithm is adaptive to point contention, if its RMR complexity is a function of the maximum number of processes concurrently executing their entry, critical, or exit section. In the best prior art deterministic adaptive mutual exclusion algorithm, presented by Kim and Anderson [22], a process performs O(min(k,log N)) RMRs as it enters and exits its critical section, where k is point contention and N is the number of processes in the system. Kim and Anderson also proved that a deterministic algorithm with o(k) RMR complexity does not exist [21]. However, they describe a randomized mutual exclusion algorithm that has O(log k) expected RMR complexity against an oblivious adversary. All these results apply for algorithms that use only atomic read and write operations. We present a randomized adaptive mutual exclusion algorithms with O(log k/loglog k) expected amortized RMR complexity, even against a strong adversary, for the cache-coherent shared memory read/write model. Using techniques similar to those used in [17], our algorithm can be adapted for the distributed shared memory read/write model. This establishes that sub-logarithmic adaptive mutual exclusion, using reads and writes only, is possible.
{"title":"Adaptive randomized mutual exclusion in sub-logarithmic expected time","authors":"Danny Hendler, Philipp Woelfel","doi":"10.1145/1835698.1835737","DOIUrl":"https://doi.org/10.1145/1835698.1835737","url":null,"abstract":"Mutual exclusion is a fundamental distributed coordination problem. Shared-memory mutual exclusion research focuses on local-spin algorithms and uses the remote memory references (RMRs) metric. A mutual exclusion algorithm is adaptive to point contention, if its RMR complexity is a function of the maximum number of processes concurrently executing their entry, critical, or exit section. In the best prior art deterministic adaptive mutual exclusion algorithm, presented by Kim and Anderson [22], a process performs O(min(k,log N)) RMRs as it enters and exits its critical section, where k is point contention and N is the number of processes in the system. Kim and Anderson also proved that a deterministic algorithm with o(k) RMR complexity does not exist [21]. However, they describe a randomized mutual exclusion algorithm that has O(log k) expected RMR complexity against an oblivious adversary. All these results apply for algorithms that use only atomic read and write operations. We present a randomized adaptive mutual exclusion algorithms with O(log k/loglog k) expected amortized RMR complexity, even against a strong adversary, for the cache-coherent shared memory read/write model. Using techniques similar to those used in [17], our algorithm can be adapted for the distributed shared memory read/write model. This establishes that sub-logarithmic adaptive mutual exclusion, using reads and writes only, is possible.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"245 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":"121459923","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 describe a simple framework, called the transitive closure framework (TCF), for the self-stabilizing construction of any overlay network. The TCF is easy to reason about and algorithms derived from it stabilize within O(log n) more rounds than the optimal. As evidence of the power of this framework, we derive from the TCF a simple, self-stabilizing protocol for constructing Skip + graphs in O(log n) rounds.
{"title":"Brief announcement: a framework for building self-stabilizing overlay networks","authors":"Andrew Berns, Sukumar Ghosh, S. Pemmaraju","doi":"10.1145/1835698.1835790","DOIUrl":"https://doi.org/10.1145/1835698.1835790","url":null,"abstract":"We describe a simple framework, called the transitive closure framework (TCF), for the self-stabilizing construction of any overlay network. The TCF is easy to reason about and algorithms derived from it stabilize within O(log n) more rounds than the optimal. As evidence of the power of this framework, we derive from the TCF a simple, self-stabilizing protocol for constructing Skip + graphs in O(log n) rounds.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"85 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":"129214278","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":"E. Rupert","doi":"10.1145/3258207","DOIUrl":"https://doi.org/10.1145/3258207","url":null,"abstract":"","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"24 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":"121865079","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}
P. O'Hearn, N. Rinetzky, Martin T. Vechev, Eran Yahav, G. Yorsh
We present a proof of safety and linearizability of a highly-concurrent optimistic set algorithm. The key step in our proof is the Hindsight Lemma, which allows a thread to infer the existence of a global state in which its operation can be linearized based on limited local atomic observations about the shared state. The Hindsight Lemma allows us to avoid one of the most complex and non-intuitive steps in reasoning about highly concurrent algorithms: considering the linearization point of an operation to be in a different thread than the one executing it. The Hindsight Lemma assumes that the algorithm maintains certain simple invariants which are resilient to interference, and which can themselves be verified using purely thread-local proofs. As a consequence, the lemma allows us to unlock a perhaps-surprising intuition: a high degree of interference makes non-trivial highly-concurrent algorithms in some cases much easier to verify than less concurrent ones.
{"title":"Verifying linearizability with hindsight","authors":"P. O'Hearn, N. Rinetzky, Martin T. Vechev, Eran Yahav, G. Yorsh","doi":"10.1145/1835698.1835722","DOIUrl":"https://doi.org/10.1145/1835698.1835722","url":null,"abstract":"We present a proof of safety and linearizability of a highly-concurrent optimistic set algorithm. The key step in our proof is the Hindsight Lemma, which allows a thread to infer the existence of a global state in which its operation can be linearized based on limited local atomic observations about the shared state. The Hindsight Lemma allows us to avoid one of the most complex and non-intuitive steps in reasoning about highly concurrent algorithms: considering the linearization point of an operation to be in a different thread than the one executing it. The Hindsight Lemma assumes that the algorithm maintains certain simple invariants which are resilient to interference, and which can themselves be verified using purely thread-local proofs. As a consequence, the lemma allows us to unlock a perhaps-surprising intuition: a high degree of interference makes non-trivial highly-concurrent algorithms in some cases much easier to verify than less concurrent ones.","PeriodicalId":447863,"journal":{"name":"Proceedings of the 29th ACM SIGACT-SIGOPS symposium on Principles of distributed computing","volume":"19 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":"125206847","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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