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15
Sharedmemory mutual exclusion: Major research trends since
 Distributed Computing
, 1986
"... * Exclusion: At most one process executes its critical section at any time. ..."
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Cited by 47 (7 self)
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* Exclusion: At most one process executes its critical section at any time.
Adaptive and Efficient Algorithms for Lattice Agreement and Renaming
 SIAM J. Comput
, 1998
"... In a sharedmemory system, n independent asynchronous processes, with distinct names in the range {0, ..., N  1}, communicate by reading and writing to shared registers. An algorithm is waitfree if a process completes its execution regardless of the behavior of other processes. This paper consider ..."
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Cited by 22 (7 self)
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In a sharedmemory system, n independent asynchronous processes, with distinct names in the range {0, ..., N  1}, communicate by reading and writing to shared registers. An algorithm is waitfree if a process completes its execution regardless of the behavior of other processes. This paper considers waitfree algorithms whose complexity adjusts to the level of contention in the system: An algorithm is adaptive (to total contention) if its step complexity depends only on the actual number of active processes, k; this number is unknown in advance and may change in different executions of the algorithm. Adaptive algorithms are presented for two important decision problems, lattice agreement and (6k  1)renaming; the step complexity of both algorithms is O(k log k). An interesting component of the (6k  1)renaming algorithm is an O(N) algorithm for (2k  1)renaming; this improves on the best previously known (2k  1)renaming algorithm, which has O(Nnk) s...
Efficient Adaptive Collect using Randomization
 PROC. OF THE INTL. SYMP. ON DISTRIBUTED COMPUTING (DISC
, 2004
"... An adaptive algorithm, whose step complexity adjusts to the number of active processes, is attractive for distributed systems with a highlyvariable number of processes. The cornerstone of many adaptive algorithms is an adaptive mechanism to collect uptodate information from all participating p ..."
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Cited by 17 (2 self)
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An adaptive algorithm, whose step complexity adjusts to the number of active processes, is attractive for distributed systems with a highlyvariable number of processes. The cornerstone of many adaptive algorithms is an adaptive mechanism to collect uptodate information from all participating processes. To date, all known collect algorithms either have nonlinear step complexity or they are impractical because of unrealistic memory overhead. This paper
A Simple Algorithmic Characterization of Uniform Solvability (Extended Abstract)
 Proceedings of the 43rd Annual IEEE Symposium on Foundations of Computer Science (FOCS 2002
, 2002
"... The HerlihyShavit (HS) conditions characterizing the solvability of asynchronous tasks over n processors have been a milestone in the development of the theory of distributed computing. Yet, they were of no help when researcher sought algorithms that do not depend on n. To help in this pursuit we i ..."
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Cited by 11 (6 self)
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The HerlihyShavit (HS) conditions characterizing the solvability of asynchronous tasks over n processors have been a milestone in the development of the theory of distributed computing. Yet, they were of no help when researcher sought algorithms that do not depend on n. To help in this pursuit we investigate the uniform solvability of an infinite uniform sequence of tasks T 0 , T 1 , T 2 , ..., where T i is a task over processors p 0 , p 1 , ..., p i , and T i extends T i1 . We say that such a sequence is uniformly solvable if there exit protocols to solve each T i and the protocol for T i extends the protocol for T i1 . This paper establishes that although each T i may be solvable, the uniform sequence is not necessarily uniformly solvable. We show this by proposing a novel uniform sequence of solvable tasks and proving that the sequence is not amenable to a uniform solution. We then extend the HS conditions for a task over n processors, to uniform solvability in a natural way. The technique we use to accomplish this is to generalize the alternative algorithmic proof, by Borowsky and Gafni, of the HS conditions, by showing that the infinite uniform sequence of task of Immediate Snapshots is uniformly solvable. A side benefit of the technique is a widely applicable methodology for the development of uniform protocols.
Lamport on Mutual Exclusion: 27 Years of Planting Seeds
 In 20th ACM Symposium on Principles of Distributed Computing
, 2001
"... Mutual exclusion is a topic that Leslie Lamport has returned to many times throughout his career. This article, which is being written in celebration of Lamport's sixtieth birthday, is an attempt to survey some of his many contributions to research on this topic. ..."
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Cited by 9 (0 self)
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Mutual exclusion is a topic that Leslie Lamport has returned to many times throughout his career. This article, which is being written in celebration of Lamport's sixtieth birthday, is an attempt to survey some of his many contributions to research on this topic.
Uniform solvability with a finite number of mwmr registers
 In Proceedings of the 17th International Conference on Distributed Computing
, 2003
"... Abstract. This paper introduces a new interesting research question concerning tasks. The weaktestandset task has a uniform solution that requires only two MultiWriter MultiReader (MWMR) registers. Recently it was shown that if we take the longlived version and require a step complexity that i ..."
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Cited by 7 (5 self)
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Abstract. This paper introduces a new interesting research question concerning tasks. The weaktestandset task has a uniform solution that requires only two MultiWriter MultiReader (MWMR) registers. Recently it was shown that if we take the longlived version and require a step complexity that is adaptive to interval contention then, like mutual exclusion, no solution with finitely many MWMR registers is possible. Here we show that there are simple tasks which provably cannot be solved uniformly with finitely many MWMR registers. This opens up the research question of when a task is uniformly solvable using only finitely many MWMR registers. 1
An O(1) RMRs leader election algorithm
 In Proc. ACM PODC 2006
, 2006
"... The leader election problem is a fundamental coordination problem. We present leader election algorithms for multiprocessor systems where processes communicate by reading and writing shared memory asynchronously, and do not fail. In particular, we consider the cachecoherent (CC) and distributed shar ..."
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Cited by 6 (2 self)
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The leader election problem is a fundamental coordination problem. We present leader election algorithms for multiprocessor systems where processes communicate by reading and writing shared memory asynchronously, and do not fail. In particular, we consider the cachecoherent (CC) and distributed shared memory (DSM) models of such systems. We present leader election algorithms that perform a constant number of remote memory references (RMRs) in the worst case. Our algorithms use splitterlike objects [6, 9] in a novel way, by organizing active processes into teams that share work. As there is an Ω(log n) lower bound on the RMR complexity of mutual exclusion for n processes using reads and writes only [10], our result separates the mutual exclusion and leader election problems in terms of RMR complexity in both the CC and DSM models. Our result also implies that any algorithm using reads, writes and onetime testandset objects can be simulated by an algorithm using reads and writes with only a constant blowup of the RMR complexity; proving this is easy in the CC model, but presents subtle challenges in
Computing with infinitely many processes under assumptions on concurrency and participation
 In 14th Int. Symp. on DIStributed Comp. (DISC
, 2000
"... We explore four classic problems in concurrent computing (election, mutual exclusion, consensus, and naming) when the number of processes which may participate is infinite. Partial information about the number of actually participating processes and the concurrency level is shown to affect the possi ..."
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Cited by 5 (0 self)
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We explore four classic problems in concurrent computing (election, mutual exclusion, consensus, and naming) when the number of processes which may participate is infinite. Partial information about the number of actually participating processes and the concurrency level is shown to affect the possibility and complexity of solving these problems. We survey and generalize work carried out in models with finite bounds on the number of processes, and prove several new results. These include improved bounds for election when participation is required (even for finitely many processes, as investigated by Styer and Peterson [SP89]) and a new adaptive starvationfree mutual exclusion algorithm for unbounded concurrency. We survey results in models with shared objects stronger than atomic registers, such as test&set bits, semaphores or readmodifywrite registers, and update them for the infinite process case.
Adaptive Randomized Mutual Exclusion in SubLogarithmic Expected Time ABSTRACT
"... Mutual exclusion is a fundamental distributed coordination problem. Sharedmemory mutual exclusion research focuses on localspin 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 m ..."
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Cited by 4 (0 self)
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Mutual exclusion is a fundamental distributed coordination problem. Sharedmemory mutual exclusion research focuses on localspin 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 / log log k) expected amortized RMR complexity, even against a strong adversary, for the cachecoherent 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 sublogarithmic adaptive mutual exclusion, using reads and writes only, is possible.
Resilient consensus for infinitely many processes
 In Proceedings of the 17 th International Symposium on Distributed Computing (DISC’03
, 2003
"... Abstract. We provide results for implementing resilient consensus for a (countably) infinite collection of processes. – For a known number of faults, we prove the following equivalence result: For every t ≥ 1, there is a tresilient consensus object for infinitely many processes if and only if there ..."
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Cited by 3 (1 self)
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Abstract. We provide results for implementing resilient consensus for a (countably) infinite collection of processes. – For a known number of faults, we prove the following equivalence result: For every t ≥ 1, there is a tresilient consensus object for infinitely many processes if and only if there is a tresilient consensus object for t + 1 processes. – For an unknown or infinite number of faults, we consider whether an infinite set of waitfree consensus objects, capable of solving consensus for any finite collection of processes, suffice to solve waitfree consensus for infinitely many processes. We show that this implication holds under an assumption precluding runs in which the number of simultaneously active processes is not bounded, leaving the general question open. All the proofs are constructive and several of the constructions have adaptive time complexity. (Reduced to the finite domain, some improve on the time complexity of known results.) Furthermore, we prove that the constructions are optimal in some space parameters by providing tight simultaneousaccess and space lower bounds. Finally, using known techniques, we draw new conclusions on the universality of resilient consensus objects in the infinite domain. 1