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We study oblivious deterministic gossip algorithms for multi-channel radio networks with a malicious adversary. In a multi-channel network, each of the n processes in the system must choose, in each round, one of the c channels of the system on which to participate. Assuming the adversary can disrupt one channel per round, preventing communication on that(More)
Set agreement is a fundamental problem in distributed computing in which processes collectively choose a small subset of values from a larger set of proposals. The impossibility of fault-tolerant set agreement in asynchronous networks is one of the seminal results in distributed computing. In synchronous networks, too, the complexity of set agreement has(More)
Software transactional memory (STM) systems use lightweight, in-memory software transactions to address concurrency in multi-threaded applications, ensuring safety at all times. A contention manager is responsible for the system as a whole to make progress (liveness). In this paper, we study the impact of transaction failures on contention management in the(More)
So far, the distributed computing community has either assumed that all the processes of a distributed system have distinct identifiers or, more rarely, that the processes are anonymous and have no identifiers. These are two extremes of the same general model: namely, <i>n</i> processes use <i>l</i> different authenticated identifiers, where 1 &#8804;(More)
Conducting a thorough performance evaluation of an STM is very time consuming. Depressingly, even with all this effort, and even with the same application, it can still be hard to predict the performance if the number of underlying threads on which the application needs to be deployed is different than those of the experiment. Basically , one might have to(More)
Software transactional memory (STM) is a promising technique for writing concurrent programs. So far, most STM approaches have been experimentally evaluated with small-scale µbenchmarks. In this paper, we present several surprising results from implementing and experimenting with STMBench7 – a large scale benchmark for STMs. First, all STMs we used crashed,(More)
We propose a new mechanism to preserve privacy while leveraging user profiles in distributed recommender systems. Our mechanism relies on two contributions: (i) an original obfuscation scheme, and (ii) a randomized dissemination protocol. We show that our obfuscation scheme hides the exact profiles of users without significantly decreasing their utility for(More)
The fair exchange problem is key to trading electronic items in systems of mutually untrusted parties. We consider modern variants of such systems where each party is equipped with a tamper proof security module. The security modules trust each other but can only communicate by exchanging messages through their host parties. These are untrusted and could(More)
A three-tier application is organized as three layers. Front end clients (e.g., browsers) with which human user interactt middle-tier servers (e.g., web servers) that contain the core business logic of the applicationn and back-end database servers against which application servers perform transactions. Although three-tier applications are nowadays(More)