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Backoff protocols for distributed mutual exclusion and ordering
 Proceedings of the 21st International Conference on Distributed Computing Systems
, 2001
"... We present a simple and efficient protocol for mutual exclusion in synchronous, messagepassing distributed systems subject to failures. Our protocol borrows design principles from prior work in backoff protocols for multiple access channels such as Ethernet. Our protocol is adaptive in that the exp ..."
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Cited by 32 (11 self)
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We present a simple and efficient protocol for mutual exclusion in synchronous, messagepassing distributed systems subject to failures. Our protocol borrows design principles from prior work in backoff protocols for multiple access channels such as Ethernet. Our protocol is adaptive in that the expected amortized system response time— informally, the average time a process waits before entering the critical section—is a function only of the number of clients currently contending and is independent of the maximum number of processes who might contend. In particular, in the contentionfree case, a process can enter the critical section after only one roundtrip message delay. We use this protocol to derive a protocol for ordering operations on a replicated object in an asynchronous distributed system subject to failures. This protocol is always safe, is probabilistically live during periods of stability, and is suitable for deployment in practical systems. 1
TimeAdaptive Algorithms for Synchronization
 SIAM J. Comput
, 1994
"... We consider concurrent systems in which there is an unknown upper bound on memory access time. Such a model is inherently different from asynchronous model where no such bound exists, and also from timingbased models where such a bound exists and is known a priori. The appeal of our model lies in t ..."
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Cited by 24 (5 self)
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We consider concurrent systems in which there is an unknown upper bound on memory access time. Such a model is inherently different from asynchronous model where no such bound exists, and also from timingbased models where such a bound exists and is known a priori. The appeal of our model lies in the fact that while it abstracts from implementation details, it is a better approximation of real concurrent systems compared to the asynchronous model. Furthermore, it is stronger than the asynchronous model enabling us to design algorithms for problems that are unsolvable in the asynchronous model. Two basic synchronization problems, consensus and mutual exclusion, are investigated in a shared memory environment that supports atomic read/write registers. We show that \Theta(\Delta log \Delta log log \Delta ) is an upper and lower bound on the time complexity of consensus, where \Delta is the (unknown) upper bound on memory access time. For the mutual exclusion problem, we design an effic...
Computing in the presence of timing failures
 In Proceedings of theInternational Conference on Distributed Computing Systems (DCS
, 2007
"... Timing failures refer to a situation where the environment in which a system operates does not behave as expected regarding the timing assumptions, that is, the timing constraints are not met. In the immense body of work on the designing faulttolerant systems, the type of failures that are usually ..."
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Cited by 4 (1 self)
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Timing failures refer to a situation where the environment in which a system operates does not behave as expected regarding the timing assumptions, that is, the timing constraints are not met. In the immense body of work on the designing faulttolerant systems, the type of failures that are usually considered are, process failures, link failures, messages loss and memory failures; and it is usually (implicitly) assumed that there are no timing failures. In this paper we investigate the ability to recover automatically from transient timing failures. We introduce and formally define the concept of algorithms that are resilient to timing failures, and demonstrate the importance of the new concept by presenting consensus and mutual exclusion algorithms, using atomic registers only, that are resilient to timing failures.
Timingbased mutual exclusion with local spinning
 In 17th international symposium on distributed computing, October 2003. LNCS 2848
, 2003
"... Abstract We consider the time complexity of sharedmemory mutual exclusion algorithms based on reads, writes, and comparison primitives under the remotememoryreference (RMR) time measure. For asynchronous systems, a lower bound of \Omega (log N / log log N) RMRs per criticalsection entry has been ..."
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Cited by 3 (0 self)
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Abstract We consider the time complexity of sharedmemory mutual exclusion algorithms based on reads, writes, and comparison primitives under the remotememoryreference (RMR) time measure. For asynchronous systems, a lower bound of \Omega (log N / log log N) RMRs per criticalsection entry has been established in previous work, where N is the number of processes. Also, algorithms with O(log N) time complexity are known. Thus, for algorithms in this class, logarithmic or nearlogarithmic RMR time complexity is fundamentally required.
Teaching Concurrency: Theory in Practice ⋆
"... Abstract. Teaching courses that rely on sound mathematical principles is nowadays a challenging task at many universities. On the one hand there is an increased demand for educating students in these areas, on the other hand there are more and more students being accepted with less adequate skills i ..."
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Abstract. Teaching courses that rely on sound mathematical principles is nowadays a challenging task at many universities. On the one hand there is an increased demand for educating students in these areas, on the other hand there are more and more students being accepted with less adequate skills in mathematics. We report here on our experiences in teaching concurrency theory over the last twenty years or so to students ranging from mathsphobic bachelor students to sophisticated doctoral students. The contents of the courses, the material on which they are based and the pedagogical philosophy underlying them are described, as well as some of the lessons that we have learned over the years. 1 Introduction and
Using Delays to Improve RMR Time Complexity in Mutual Exclusion Algorithms (Extended Abstract)
"... We consider the time complexity of sharedmemory mutual exclusion algorithms under the remotememoryreference (RMR) time measure. In particular, algorithms based on reads, writes, and comparison primitives are considered. For such algorithms, a lower bound of \Omega(log N/ log log N) RMRs per criti ..."
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We consider the time complexity of sharedmemory mutual exclusion algorithms under the remotememoryreference (RMR) time measure. In particular, algorithms based on reads, writes, and comparison primitives are considered. For such algorithms, a lower bound of \Omega(log N/ log log N) RMRs per criticalsection entry has been established in previous work, where N is the number of processes. Also, algorithms with O(log N) time complexity are known. Thus, for algorithms in this class, logarithmic or nearlogarithmic RMR time complexity is fundamentally required. In this paper, we consider...
Fairness of Shared Objects (Extended Abstract)
"... ) Michael Merritt ? Gadi Taubenfeld ?? Abstract. Fairness in concurrent systems can be viewed as an abstraction that bridges lowlevel timing guarantees and make them available to programmers with a minimal loss of power and a maximal ease of use. We investigate the implementation and power ..."
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) Michael Merritt ? Gadi Taubenfeld ?? Abstract. Fairness in concurrent systems can be viewed as an abstraction that bridges lowlevel timing guarantees and make them available to programmers with a minimal loss of power and a maximal ease of use. We investigate the implementation and power of a range of fairness models that are appropriate to the synchronous, semisynchronous and asynchronous contexts of various concurrent systems. 1 Introduction 1.1 Motivation Fairness is a powerful abstraction that has led to fruitful results in the theory of concurrent, distributed and nondeterministic programs. Various notions of fairness can be explained very briefly, but small differences have important consequences on the computability and complexity of concurrent systems. We investigate the implementation and power of a range of fairness models that are appropriate to the synchronous, semisynchronous and asynchronous contexts of various concurrent systems. While some previous wo...
The Impact of Timing Knowledge on the Session Problem
"... The session problem is an abstraction of fundamental synchronization problems in distributed systems. It has previously been used as a testcase to demonstrate the differences in the time needed to solve problems in several timing models. ..."
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The session problem is an abstraction of fundamental synchronization problems in distributed systems. It has previously been used as a testcase to demonstrate the differences in the time needed to solve problems in several timing models.