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Rachid Guerraoui

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Related publications (292)

Efficient Multi-Word Compare and Swap

Atomic lock-free multi-word compare-and-swap (MCAS) is a powerful tool for designing concurrent algorithms. Yet, its widespread usage has been limited because lock-free implementations of MCAS make heavy use of expensive compare-and-swap (CAS) instructions ...

Schloss Dagstuhl, Leibniz-Zentrum2020

Robust P2P Personalized Learning

Rachid Guerraoui, Yahya Benkaouz

Decentralized machine learning over peer-to-peer networks is very appealing for it enables to learn personalized models without sharing users data, nor relying on any central server. Peers can improve upon their locally trained model across a network graph ...

IEEE2020

Byzantine machine learning

Rachid Guerraoui, El Mahdi El Mhamdi, Mahsa Taziki, Sébastien Louis Alexandre Rouault

The present invention concerns computer-implemented methods for training a machine learning model using Stochastic Gradient Descent, SGD. In one embodiment, the method is performed by a first computer in a distributed computing environment and comprises pe ...

2020

Microsecond Consensus for Microsecond Applications

Rachid Guerraoui, Mihail Igor Zablotchi, Athanasios Xygkis, Naama Ben David

We consider the problem of making apps fault-tolerant through replication, when apps operate at the microsecond scale, as in finance, embedded computing, and microservices apps. These apps need a replication scheme that also operates at the microsecond sca ...

USENIX ASSOC2020

Byzantine tolerant gradient descent for distributed machine learning with adversaries

Rachid Guerraoui, El Mahdi El Mhamdi, Peva François Blanchard, Julien Michel Stainer

The present application concerns a computer-implemented method for training a machine learning model in a distributed fashion, using Stochastic Gradient Descent, SGD, wherein the method is performed by a first computer in a distributed computing environmen ...

2019

The Fake News Vaccine

Rachid Guerraoui, Willy Zwaenepoel, Anne-Marie Kermarrec, Oana Maria Balmau, Matej Pavlovic, Alexandre David Olivier Maurer

While spreading fake news is an old phenomenon, today social media enables misinformation to instantaneously reach millions of people. Content-based approaches to detect fake news, typically based on automatic text checking, are limited. It is indeed diffi ...

2019

Unified and Scalable Incremental Recommenders with Consumed Item Packs

Rachid Guerraoui, Rhicheek Patra

Recommenders personalize the web content using collaborative filtering to relate users (or items). This work proposes to unify user-based, item-based and neural word embeddings types of recommenders under a single abstraction for their input, we name Consu ...

Springer2019

The Impact of RDMA on Agreement

Rachid Guerraoui, Mihail Igor Zablotchi, Naama Ben David

Remote Direct Memory Access (RDMA) is becoming widely available in data centers. This technology allows a process to directly read and write the memory of a remote host, with a mechanism to control access permissions. In this paper, we study the fundamenta ...

2019

The Consensus Number of a Cryptocurrency

Rachid Guerraoui, Matej Pavlovic, Dragos-Adrian Seredinschi, Matteo Monti

Many blockchain-based algorithms, such as Bitcoin, implement a decentralized asset transfer system, often referred to as a cryptocurrency. As stated in the original paper by Nakamoto, at the heart of these systems lies the problem of preventing double-spen ...

ASSOC COMPUTING MACHINERY2019

Distributed Transactional Systems Cannot Be Fast

Rachid Guerraoui, Willy Zwaenepoel, Panagiota Fatourou, Junxiong Wang, Diego Didona

We prove that no fully transactional system can provide fast read transactions (including read-only ones that are considered the most frequent in practice). Specifically, to achieve fast read transactions, the system has to give up support of transactions ...

2019

Utility and privacy effects of a user action in a communication system

Rachid Guerraoui, Mahsa Taziki

The present invention concerns a method of determining an effect of a user action taken with respect to an item in a communication network. The item is associated with data content in the communication network. The method comprises: (a) determining (31) pu ...

2019

Exploring The Borderlands Of The Gathering Problem

Rachid Guerraoui, El Mahdi El Mhamdi, Alexandre David Olivier Maurer, Vladislav Tempez

Problems of pattern formation have been extensively studied in distributed computing. One of this problems is the gathering problem: agents must gather at a same position in a distributed manner. When gathering is not possible, a close problem is the conve ...

2019

Fingerprinting Big Data: The Case of KNN Graph Construction

Rachid Guerraoui, Anne-Marie Kermarrec, Olivier Ruas

We propose fingerprinting, a new technique that consists in constructing compact, fast-to-compute and privacy-preserving binary representations of datasets. We illustrate the effectiveness of our approach on the emblematic big data problem of K-Nearest-Nei ...

2019

Scalable Byzantine Reliable Broadcast

Rachid Guerraoui, Matej Pavlovic, Dragos-Adrian Seredinschi, Matteo Monti

Byzantine reliable broadcast is a powerful primitive that allows a set of processes to agree on a message from a designated sender, even if some processes (including the sender) are Byzantine. Existing broadcast protocols for this setting scale poorly, as ...

Schloss Dagstuhl--Leibniz-Zentrum fer Informatik2019

Lock-Unlock: Is That All? A Pragmatic Analysis of Locking in Software Systems

Rachid Guerraoui, Vasileios Trigonakis

A plethora of optimized mutex lock algorithms have been designed over the past 25 years to mitigate performance bottlenecks related to critical sections and locks. Unfortunately, there is currently no broad study of the behavior of these optimized lock alg ...

2019

The weakest failure detector for eventual consistency

Rachid Guerraoui, Pierre Sens

In its classical form, a consistent replicated service requires all replicas to witness the same evolution of the service state. If we consider an asynchronous messagepassing environment in which processes might fail by crashing, and assume that a majority ...

2019

AGGREGATHOR: Byzantine Machine Learning via Robust Gradient Aggregation

Rachid Guerraoui, El Mahdi El Mhamdi, Georgios Damaskinos, Sébastien Louis Alexandre Rouault, Arsany Hany Abdelmessih Guirguis

We present AGGREGATHOR, a framework that implements state-of-the-art robust (Byzantine-resilient) distributed stochastic gradient descent. Following the standard parameter server model, we assume that a minority of worker machines can be controlled by an a ...

2019

The PCL Theorem: Transactions cannot be Parallel, Consistent, and Live

Rachid Guerraoui, Victor Bushkov, Panagiota Fatourou

We establish a theorem called the PCL theorem, which states that it is impossible to design a transactional memory algorithm that ensures (1) parallelism, i.e., transactions do not need to synchronize unless they access the same application objects, (2) ve ...

ASSOC COMPUTING MACHINERY2019

Deep Learning Works in Practice. But Does it Work in Theory?

Rachid Guerraoui, Le Nguyen Hoang

Deep learning relies on a very specific kind of neural networks: those superposing several neural layers. In the last few years, deep learning achieved major breakthroughs in many tasks such as image analysis, speech recognition, natural language processin ...

2018

SPADE: Tuning scale-out OLTP on modern RDMA clusters

Rachid Guerraoui, Aleksandar Dragojevic, Georgios Chatzopoulos

Distributed transactions on modern RDMA clusters promise high throughput and low latency for scale-out workloads. As such, they can be particularly beneficial to large OLTP workloads, which require both. However, achieving good performance requires tuning ...

Association for Computing Machinery2018

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