The power of logical clock abstractions

Kshemkalyani, Ajay D.

doi:10.1007/s00446-003-0105-9

Cited by 10 publications

(4 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The state s i,x refers to the local state of P i after P i executes event e i,x , but before e i,x+1 is executed. Execution of a distributed program can be modeled as a communication graph G = (U, E), where each vertex in U refers to an event, and each edge (u, v) in E refers to the precedence relation from event u to v [9,11,12]. In the communication graph, each edge (e i,x , e i,x+1 ) in E refers to the state s i,x .…”

Section: Distributed Computationmentioning

confidence: 99%

“…Furthermore, by definition (see Definitions 3 and 4), the above equation can be rewritten as ⇔ (c c t ) (t) and (c t d) (t) ⇔ c ≺ F t (c t ) and R t (c t ) ≺ d (9) That is, every checkpoint c in the second area has new Z-paths to every checkpoint d, where d is the checkpoint having Z-paths from c t (i.e. R t (c t ) ≺ d) (see Fig.…”

Section: Lemma 6 the Z-path C C Exists In H T If And Only If C Is T-rmentioning

confidence: 99%

See 1 more Smart Citation

Efficient online algorithm for identifying useless states in distributed systems

2011

View full text Add to dashboard Cite

In a distributed system, detecting whether a given logical predicate is true on the global states is fundamental for testing and debugging the program. Detecting predicates by examining all global states is intractable due to the combinatorial nature of the problem. This work designs an efficient online algorithm that identifies the consistent and useless states each time a new state is reported. This paper formulates the optimality of detecting algorithms in terms of pseudo states, which are employed to represent unknown states to the monitor process. Based on this technique, memory space of the debugger can be minimized by removing the useless states without affecting the debugging results. While minimizing memory space, the proposed algorithm requires only O( p 2 M) time in total, where p is the number of processes, and M is the number of reported states.

show abstract

Section: Distributed Computationmentioning

confidence: 99%

Section: Lemma 6 the Z-path C C Exists In H T If And Only If C Is T-rmentioning

confidence: 99%

Efficient online algorithm for identifying useless states in distributed systems

2011

View full text Add to dashboard Cite

show abstract

“…Matrix clocks, too, have been optimized [7,30,14] and generalized [18]. We leave for (interesting) future work the question of whether agreement events such as the ones we are proposing could be generalized along similar lines.…”

Section: Related Workmentioning

confidence: 99%

Agreeing to Agree: Conflict Resolution for Optimistically Replicated Data

Greenwald

Khanna

Kunal

et al. 2006

Lecture Notes in Computer Science

View full text Add to dashboard Cite

Current techniques for reconciling disconnected changes to optimistically replicated data often use version vectors or related mechanisms to track causal histories. This allows the system to tell whether the value at one replica dominates another or whether the two replicas are in conflict. However, current algorithms do not provide entirely satisfactory ways of repairing conflicts. The usual approach is to introduce fresh events into the causal history, even in situations where the causally independent values at the two replicas are actually equal. In some scenarios these events may later conflict with each other or with further updates, slowing or even preventing convergence of the whole system.To address this issue, we enrich the set of possible actions at a replica to include a notion of explicit conflict resolution between existing events, where the user at a replica declares that one set of events dominates another, or that a set of events are equivalent. We precisely specify the behavior of this refined replication framework from a user's point of view and show that, if communication is assumed to be "reciprocal" (with pairs of replicas exchanging information about their current states), then this specification can be implemented by an algorithm with the property that the information stored at any replica and the sizes of the messages sent between replicas are bounded by a polynomial function of the number of replicas in the system.

show abstract

“…Since we verified the latter policy using traditional testing, these scenarios are already covered. On the other hand, any additional component beyond the three we use would not generate situations that cannot be mapped to a distributed execution with three components [43]. We checked property (1) using a setting without time constraints.…”

Section: B Assessing Loupe's Implementationmentioning

confidence: 99%

Loupe: Verifying Publish-Subscribe Architectures with a Magnifying Lens

Baresi

Ghezzi

Mottola

2011

IIEEE Trans. Software Eng.

View full text Add to dashboard Cite

Abstract-The Publish-Subscribe (P/S) communication paradigm fosters high decoupling among distributed components. This facilitates the design of dynamic applications, but also impacts negatively on their verification, making it difficult to reason on the overall federation of components. In addition, existing P/S infrastructures offer radically different features to the applications, e.g., in terms of message reliability. This further complicates the verification, as its outcome depends on the specific guarantees provided by the underlying P/S system. Although model checking has been proposed as a tool for the verification of P/S architectures, existing solutions overlook many characteristics of the underlying communication infrastructure to avoid state explosion problems.To overcome these limitations, the Loupe domain-specific model checker adopts a different approach. The P/S infrastructure is not modeled on top of a general-purpose model checker. Instead, it is embedded within the checking engine, and the traditional P/S operations become part of the modeling language. In this article, we describe Loupe's design and the dedicated state abstractions that enable accurate verification without incurring in state explosion problems. We also illustrate our use of state-ofthe-art software verification tools to assess some key functionality in Loupe's current implementation. A complete case study shows how Loupe eases the verification of P/S architectures. Finally, we quantitatively compare Loupe's performance against alternative approaches. The results indicate that Loupe is effective and efficient in enabling accurate verification of P/S architectures.

show abstract

The power of logical clock abstractions

Cited by 10 publications

References 26 publications

Efficient online algorithm for identifying useless states in distributed systems

Efficient online algorithm for identifying useless states in distributed systems

Agreeing to Agree: Conflict Resolution for Optimistically Replicated Data

Loupe: Verifying Publish-Subscribe Architectures with a Magnifying Lens

Contact Info

Product

Resources

About