Coordinating Phased Activities while Maintaining Progress

Cogumbreiro, Tiago; Martins, Francisco; Vasconcelos, Vasco T.

doi:10.1007/978-3-642-38493-6_3

Cited by 6 publications

(9 citation statements)

References 15 publications

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“…Producer-Consumer. A primary motivation for phasers is to support asynchronous producerconsumer patterns [14,64] that cannot be expressed using the barrier features discussed in Section 2.2. Such synchronisation patterns occur in programs performing streaming (also known as dataflow) communication among tasks [54,60,63].…”

Section: Generalised Barrier Synchronisation Using Phasersmentioning

confidence: 99%

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Dynamic Deadlock Verification for General Barrier Synchronisation

Cogumbreiro

Martins

et al. 2018

ACM Trans. Program. Lang. Syst.

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We present Armus, a verification tool for dynamically detecting or avoiding barrier deadlocks. The core design of Armus is based on phasers, a generalisation of barriers that supports split-phase synchronisation, dynamic membership, and optional-waits. This allows Armus to handle the key barrier synchronisation patterns found in modern languages and libraries. We implement Armus for X10 and Java, giving the first sound and complete barrier deadlock verification tools in these settings. Armus introduces a novel event-based graph model of barrier concurrency constraints that distinguishes task-event and event-task dependencies. Decoupling these two kinds of dependencies facilitates the verification of distributed barriers with dynamic membership, a challenging feature of X10. Further, our base graph representation can be dynamically switched between a task-to-task model, Wait-for Graph (WFG), and an event-to-event model, State Graph (SG), to improve the scalability of the analysis. Formally, we show that the verification is sound and complete with respect to the occurrence of deadlock in our core phaser language, and that switching graph representations preserves the soundness and completeness properties. These results are machine checked with the Coq proof assistant. Practically, we evaluate the runtime overhead of our implementations using three benchmark suites in local and distributed scenarios. Regarding deadlock detection, distributed scenarios show negligible overheads and local scenarios show overheads below 1.15×. Deadlock avoidance is more demanding, and highlights the potential gains from dynamic graph selection. In one benchmark scenario, the runtime overheads vary from 1.8× for dynamic selection, 2.6× for SG-static selection, and 5.9× for WFG-static selection.

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Section: Generalised Barrier Synchronisation Using Phasersmentioning

confidence: 99%

“…The deadlock checker, following steps (1)-(3), implements the core functionality for compiling the wait-for and impede-by dependencies from the blocking statuses, graph model selection and construction, and cycle detection. We use JGraphT 14 to perform cycle detection.…”

Section: Verification Layermentioning

confidence: 99%

Dynamic Deadlock Verification for General Barrier Synchronisation

Cogumbreiro

Martins

et al. 2018

ACM Trans. Program. Lang. Syst.

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“…Similar approaches have been successfully used for Web-Services [10,38,33], and Multicore Programming [28,13]. The considerations on CPS used in this work come from well-established sources [2,37].…”

Section: Towards a Language For Cps Communicationsmentioning

confidence: 99%

“…Our work differs from these approaches in that our model focuses considers explicit considerations on availability for the systems in consideration. Also for multicore programming, the work in [13] presents a calculus with fork/join communication primitives, with a flexible phaser mechanism that allows some threads to advance prior to synchronization. The type system guarantees a node-centric progress guarantee, ideal for multicore computing, but too coarse for CPS.…”

Section: Related Workmentioning

confidence: 99%

Enforcing Availability in Failure-Aware Communicating Systems

López

Nielson

2016

Formal Techniques for Distributed Objects, Components, and Systems

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Abstract. Choreographic programming is a programming-language design approach that drives error-safe protocol development in distributed systems. Motivated by challenging scenarios in Cyber-Physical Systems (CPS), we study how choreographic programming can cater for dynamic infrastructures where the availability of components may change at runtime. We introduce the Global Quality Calculus (GCq), a process calculus featuring novel operators for multiparty, partial and collective communications; we provide a type discipline that controls how partial communications refer only to available components; and we show that well-typed choreographies enjoy progress.

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“…Finally, related work on "barrier matching" tackles the problem of barrier deadlocks in a setting where there is only global barrier synchronisation [19,47]. Cogumbreiro et al [8] propose a static typing system to ensure the correctness of phased activities for a fragment of X10 that disallows awaiting on a particular clock. Therefore, programs that involve more than one clock and that perform single waits cannot be expressed, nor verified (cf.…”

Section: Related Workmentioning

confidence: 99%

Dynamic deadlock verification for general barrier synchronisation

Cogumbreiro

Martins

et al. 2015

Proceedings of the 20th ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming

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We present Armus, a dynamic verification tool for deadlock detection and avoidance specialised in barrier synchronisation. Barriers are used to coordinate the execution of groups of tasks, and serve as a building block of parallel computing. Our tool verifies more barrier synchronisation patterns than current state-of-the-art. To improve the scalability of verification, we introduce a novel eventbased representation of concurrency constraints, and a graph-based technique for deadlock analysis. The implementation is distributed and fault-tolerant, and can verify X10 and Java programs.To formalise the notion of barrier deadlock, we introduce a core language expressive enough to represent the three most widespread barrier synchronisation patterns: group, split-phase, and dynamic membership. We propose a graph analysis technique that selects from two alternative graph representations: the Wait-For Graph, that favours programs with more tasks than barriers; and the State Graph, optimised for programs with more barriers than tasks. We prove that finding a deadlock in either representation is equivalent, and that the verification algorithm is sound and complete with respect to the notion of deadlock in our core language.Armus is evaluated with three benchmark suites in local and distributed scenarios. The benchmarks show that graph analysis with automatic graph-representation selection can record a 7-fold execution increase versus the traditional fixed graph representation. The performance measurements for distributed deadlock detection between 64 processes show negligible overheads.

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Coordinating Phased Activities while Maintaining Progress

Cited by 6 publications

References 15 publications

Dynamic Deadlock Verification for General Barrier Synchronisation

Dynamic Deadlock Verification for General Barrier Synchronisation

Enforcing Availability in Failure-Aware Communicating Systems

Dynamic deadlock verification for general barrier synchronisation

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