Tushar Deepak Chandra

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We introduce the concept of unreliable failure detectors and study how they can be used to solve Consensus in asynchronous systems with crash failures. We characterise unreliable failure detectors in terms of two properties—completeness and accuracy. We show that Consensus can be solved even with unreliable failure detectors that make an infinite(More)
We determine what information about failures is necessary and sufficient to solve Consensus in asynchronous distributed systems subject to crash failures. In Chandra and Toueg [1996], it is shown that <italic>W</italic>, a failure detector that provides surprisingly little information about which processes have crashed, is sufficient to solve Consensus in(More)
Content-based subscription systems are an emerging alternative to traditional publish-subscribe systems, because they permit more flexible subscriptions along multiple dimensions. In these systems, each subscription is a predicate which may test arbitrary attributes within an event. However, the matching problem for content-based systems — determining for(More)
The publish/subscribe (or pub/sub) paradigm is a simple and easy to use model for interconnecting applications in a distributed environment. Many existing pub/sub systems are based on pre-defined subjects, and hence are able to exploit multicast technologies to provide scalability and availability. An emerging alternative to subject-based systems, known as(More)
We describe our experience in building a fault-tolerant data-base using the Paxos consensus algorithm. Despite the existing literature in the field, building such a database proved to be non-trivial. We describe selected algorithmic and engineering problems encountered, and the solutions we found for them. Our measurements indicate that we have built a(More)
Failure Detectors for Asynchronous Systems* (Preliminary Version) Tushar Deepak Chandra and Sam Toueg Department of Computer Science Upson Hall, Cornell University Ithaca, New York 14853 chandra, samacs. cornell. edu We introduce the concept of failure detectors for asynchronous syst ems with crash failures. We show that even with a failure detector that(More)
Process groups in distributed applications and services rely on failure detectors to detect process failures <i>completely</i>, and as <i>quickly, accurately</i>, and <i>scalably</i> as possible, even in the face of unreliable message deliveries. In this paper, we look at quantifying the optimal scalability, in terms of network load, (in messages per(More)
Gryphon is a distributed computing paradigm for message brokering, which is the transferring of information in the form of streams of events from information providers to information consumers. This abstract outlines the major problems in message brokering and Gryphon's approach to solving them. In Gryphon, the flow of streams of events is described via an(More)
I present the first randomized wait-free implementation of consensus from multiple writer zmltiple reader register in which each process takes polylog (0(log2 n)) expected steps. To achieve this result, I assume a non-standard type of adversary (from [Abr88]). I argue that this type of adversary (which is more powerful than the oblivious adversary, but(More)