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WaitFree Synchronization
 ACM Transactions on Programming Languages and Systems
, 1993
"... A waitfree implementation of a concurrent data object is one that guarantees that any process can complete any operation in a finite number of steps, regardless of the execution speeds of the other processes. The problem of constructing a waitfree implementation of one data object from another lie ..."
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Cited by 876 (28 self)
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A waitfree implementation of a concurrent data object is one that guarantees that any process can complete any operation in a finite number of steps, regardless of the execution speeds of the other processes. The problem of constructing a waitfree implementation of one data object from another lies at the heart of much recent work in concurrent algorithms, concurrent data structures, and multiprocessor architectures. In the first part of this paper, we introduce a simple and general technique, based on reduction to a consensus protocol, for proving statements of the form "there is no waitfree implementation of X by Y ." We derive a hierarchy of objects such that no object at one level has a waitfree implementation in terms of objects at lower levels. In particular, we show that atomic read/write registers, which have been the focus of much recent attention, are at the bottom of the hierarchy: they cannot be used to construct waitfree implementations of many simple and familiar da...
Hierarchical correctness proofs for distributed algorithms
, 1987
"... Abstract: We introduce the inputoutput automaton, a simple but powerful model of computation in asynchronous distributed networks. With this model we are able to construct modular, hierarchical correctness proofs for distributed algorithms. We de ne this model, and give aninteresting example of how ..."
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Cited by 435 (65 self)
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Abstract: We introduce the inputoutput automaton, a simple but powerful model of computation in asynchronous distributed networks. With this model we are able to construct modular, hierarchical correctness proofs for distributed algorithms. We de ne this model, and give aninteresting example of how itcan be used to construct such proofs. 1
A Methodology for Implementing Highly Concurrent Data Objects
, 1993
"... A concurrent object is a data structure shared by concurrent processes. Conventional techniques for implementing concurrent objects typically rely on critical sections: ensuring that only one process at a time can operate on the object. Nevertheless, critical sections are poorly suited for asynchro ..."
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Cited by 355 (11 self)
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A concurrent object is a data structure shared by concurrent processes. Conventional techniques for implementing concurrent objects typically rely on critical sections: ensuring that only one process at a time can operate on the object. Nevertheless, critical sections are poorly suited for asynchronous systems: if one process is halted or delayed in a critical section, other, nonfaulty processes will be unable to progress. By contrast, a concurrent object implementation is lock free if it always guarantees that some process will complete an operation in a finite number of steps, and it is wait free if it guarantees that each process will complete an operation in a finite number of steps. This paper proposes a new methodology for constructing lockfree and waitfree implementations of concurrent objects. The objectâ€™s representation and operations are written as stylized sequential programs, with no explicit synchronization. Each sequential operation is automatically transformed into a lockfree or waitfree operation using novel synchronization and memory management algorithms. These algorithms are presented for a multiple instruction/multiple data (MIMD) architecture in which n processes communicate by applying atomic read, wrzte, load_linked, and store_conditional operations to a shared memory.
Fast Randomized Consensus using Shared Memory
 Journal of Algorithms
, 1988
"... We give a new randomized algorithm for achieving consensus among asynchronous processes that communicate by reading and writing shared registers. The fastest previously known algorithm has exponential expected running time. Our algorithm is polynomial, requiring an expected O(n 4 ) operations ..."
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Cited by 136 (32 self)
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We give a new randomized algorithm for achieving consensus among asynchronous processes that communicate by reading and writing shared registers. The fastest previously known algorithm has exponential expected running time. Our algorithm is polynomial, requiring an expected O(n 4 ) operations. Applications of this algorithm include the elimination of critical sections from concurrent data structures and the construction of asymptotically unbiased shared coins.
Composite Registers
 Distributed Computing
, 1993
"... We introduce a shared data object, called a composite register, that generalizes the notion of an atomic register. A composite register is an arraylike shared data object that is partitioned into a number of components. An operation of a composite register either writes a value to a single componen ..."
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Cited by 112 (7 self)
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We introduce a shared data object, called a composite register, that generalizes the notion of an atomic register. A composite register is an arraylike shared data object that is partitioned into a number of components. An operation of a composite register either writes a value to a single component or reads the values of all components. A composite register reduces to an ordinary atomic register when there is only one component. In this paper, we show that multireader, singlewriter atomic registers can be used to implement a composite register in which there is only one writer per component. In a related paper, we show how to use the composite register construction of this paper to implement a composite register with multiple writers per component. These two constructions show that it is possible to implement a shared memory that can be read in its entirety in a single snapshot operation, without using mutual exclusion. Keywords: atomicity, atomic register, composite register, conc...
Impossibility and universality results for waitfree synchronization
, 1987
"... Impossibility and universality results for waitfree synchronization ..."
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Cited by 91 (10 self)
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Impossibility and universality results for waitfree synchronization
TimeConstrained Automata
 CONCUR '91: 2nd International Conference on Concurrency Theory, volume 527 of Lecture Notes in Computer Science
, 1991
"... ) Michael Merritt AT&T Bell Laboratories 600 Mountain Avenue Murray Hill, NJ 07974 merritt@research.att.com Francesmary Modugno School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 fmm@cs.cmu.edu Mark R. Tuttle DEC Cambridge Research Lab One Kendall Sq., Bldg. 700 Camb ..."
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Cited by 88 (0 self)
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) Michael Merritt AT&T Bell Laboratories 600 Mountain Avenue Murray Hill, NJ 07974 merritt@research.att.com Francesmary Modugno School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 fmm@cs.cmu.edu Mark R. Tuttle DEC Cambridge Research Lab One Kendall Sq., Bldg. 700 Cambridge, MA 02139 tuttle@crl.dec.com Abstract In this paper, we augment the inputoutput automaton model in order to reason about time in concurrent systems, and we prove simple properties of this augmentation. The inputoutput automata model is a useful model for reasoning about computation in concurrent and distributed systems because it allows fundamental properties such as fairness and compositionality to be expressed easily and naturally. A unique property of the model is that systems are modeled as the composition of autonomous components. This paper describes a way to add a notion of time to the model in a way that preserves these properties. The result is a simple, compositional model fo...
WaitFree Data Structures in the Asynchronous PRAM Model
 In Proceedings of the 2nd Annual Symposium on Parallel Algorithms and Architectures
, 2000
"... In the asynchronous PRAM model, processes communicate by atomically reading and writing shared memory locations. This paper investigates the extent to which asynchronous PRAM permits longlived, highly concurrent data structures. An implementation of a concurrent object is waitfree if every operati ..."
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Cited by 61 (13 self)
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In the asynchronous PRAM model, processes communicate by atomically reading and writing shared memory locations. This paper investigates the extent to which asynchronous PRAM permits longlived, highly concurrent data structures. An implementation of a concurrent object is waitfree if every operation will complete in a finite number of steps, and it is kbounded waitfree, for some k > 0, if every operation will complete within k steps. In the first part of this paper, we show that there are objects with waitfree implementations but no kbounded waitfree implementations for any k, and that there is an infinite hierarchy of objects with implementations that are kbounded waitfree but not Kbounded waitfree for some K > k. In the second part of the paper, we give an algebraic characterization of a large class of objects that do have waitfree implementations in asynchronous PRAM, as well as a general algorithm for implementing them. Our tools include simple iterative algorithms for waitfree approximate agreement and atomic snapshot.