3,375 research outputs found
Using consistent subcuts for detecting stable properties
We present a general protocol for detecting whether a property holds in a distributed system, where the property is a member of a subclass of stable properties we call the locally stable properties. Our protocol is based on a decentralized method for constructing a maximal subset of the local states that are mutually consistent, which in turn is based on a weakened version of vectored time stamps. The structure of our protocol lends itself to refinement, and we demonstrate its utility by deriving some specialized property-detection protocols, including two previously known protocols that are known to be effective
Survey on the Event Orderings Semantics Used for Distributed System
Event ordering in distributed system (DS) is disputable and proactive subject
in DS particularly with the emergence of multimedia synchronization. According
to the literature, different type of event ordering is used for different DS
mode such as asynchronous or synchronous. Recently, there are several novel
implementation of these types introduced to fulfill the demand for establishing
a certain order according to a specific criterion in DS with lighter
complexity.Comment: 9 page
A Study of Concurrency Bugs and Advanced Development Support for Actor-based Programs
The actor model is an attractive foundation for developing concurrent
applications because actors are isolated concurrent entities that communicate
through asynchronous messages and do not share state. Thereby, they avoid
concurrency bugs such as data races, but are not immune to concurrency bugs in
general. This study taxonomizes concurrency bugs in actor-based programs
reported in literature. Furthermore, it analyzes the bugs to identify the
patterns causing them as well as their observable behavior. Based on this
taxonomy, we further analyze the literature and find that current approaches to
static analysis and testing focus on communication deadlocks and message
protocol violations. However, they do not provide solutions to identify
livelocks and behavioral deadlocks. The insights obtained in this study can be
used to improve debugging support for actor-based programs with new debugging
techniques to identify the root cause of complex concurrency bugs.Comment: - Submitted for review - Removed section 6 "Research Roadmap for
Debuggers", its content was summarized in the Future Work section - Added
references for section 1, section 3, section 4.3 and section 5.1 - Updated
citation
Rollback recovery with low overhead for fault tolerance in mobile ad hoc networks
AbstractMobile ad hoc networks (MANETs) have significantly enhanced the wireless networks by eliminating the need for any fixed infrastructure. Hence, these are increasingly being used for expanding the computing capacity of existing networks or for implementation of autonomous mobile computing Grids. However, the fragile nature of MANETs makes the constituent nodes susceptible to failures and the computing potential of these networks can be utilized only if they are fault tolerant. The technique of checkpointing based rollback recovery has been used effectively for fault tolerance in static and cellular mobile systems; yet, the implementation of existing protocols for MANETs is not straightforward. The paper presents a novel rollback recovery protocol for handling the failures of mobile nodes in a MANET using checkpointing and sender based message logging. The proposed protocol utilizes the routing protocol existing in the network for implementing a low overhead recovery mechanism. The presented recovery procedure at a node is completely domino-free and asynchronous. The protocol is resilient to the dynamic characteristics of the MANET; allowing a distributed application to be executed independently without access to any wired Grid or cellular network access points. We also present an algorithm to record a consistent global snapshot of the MANET
Inductive diagrams for causal reasoning
The Lamport diagram is a pervasive and intuitive tool for informal reasoning
about causality in a concurrent system. However, traditional axiomatic
formalizations of Lamport diagrams can be painful to work with in a mechanized
setting like Agda, whereas inductively-defined data would enjoy structural
induction and automatic normalization. We propose an alternative, inductive
formalization -- the causal separation diagram (CSD) -- that takes inspiration
from string diagrams and concurrent separation logic. CSDs enjoy a graphical
syntax similar to Lamport diagrams, and can be given compositional semantics in
a variety of domains. We demonstrate the utility of CSDs by applying them to
logical clocks -- widely-used mechanisms for reifying causal relationships as
data -- yielding a generic proof of Lamport's clock condition that is
parametric in a choice of clock. We instantiate this proof on Lamport's scalar
clock, on Mattern's vector clock, and on the matrix clocks of Raynal et al. and
of Wuu and Bernstein, yielding verified implementations of each. Our results
and general framework are mechanized in the Agda proof assistant
Submicron Systems Architecture Project: Semiannual Technical Report
No abstract available
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