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Concept

Two-phase locking

Publications associées (20)

When is it safe to run a transactional workload under Read Committed?

Christoph Koch, Bas Ketsman

The popular isolation level multiversion Read Committed (RC) exchanges some of the strong guarantees of serializability for increased transaction throughput. Nevertheless, transaction workloads can sometimes be executed under RC while still guaranteeing se ...

ASSOC COMPUTING MACHINERY2023

Improving K-means Clustering Using Speculation

Anastasia Ailamaki, Viktor Sanca, Eleni Zapridou, Stefan Igescu

K-means is one of the fundamental unsupervised data clustering and machine learning methods. It has been well studied over the years: parallelized, approximated, and optimized for different cases and applications. With increasingly higher parallelism leadi ...

2023

Efficient Protocols for Enforcing Causal Consistency in Geo-Replicated Key-Value Data Stores

Kristina Spirovska

Modern large-scale data platforms manage colossal amount of data, generated by the ever-increasing number of concurrent users. Geo-replicated and sharded key-value data stores play a central role when building such platforms. As the strongest consistency m ...

EPFL2020

Distributed Transactional Systems Cannot Be Fast

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

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

Fast General Distributed Transactions with Opacity

Aleksandar Dragojevic, Stanko Novakovic, Georgios Chatzopoulos

Transactions can simplify distributed applications by hiding data distribution, concurrency, and failures from the application developer. Ideally the developer would see the abstraction of a single large machine that runs transactions sequentially and neve ...

ASSOC COMPUTING MACHINERY2019

Scalable Synchronization in Shared-Memory Systems: Extrapolating, Adapting, Tuning

Georgios Chatzopoulos

As hardware evolves, so do the needs of applications. To increase the performance of an application, there exist two well-known approaches. These are scaling up an application, using a larger multi-core platform, or scaling out, by distributing work to mul ...

EPFL2018

Locking Timestamps versus Locking Objects

Rachid Guerraoui, Tudor Alexandru David

We present multiversion timestamp locking (MVTL), a new genre of multiversion concurrency control algorithms for serializable transactions. The key idea behind MVTL is simple: lock individual timestamps instead of locking objects. After presenting a generi ...

ASSOC COMPUTING MACHINERY2018

Universally Scalable Concurrent Data Structures

Tudor Alexandru David

The increase in the number of cores in processors has been an important trend over the past decade. In order to be able to efficiently use such architectures, modern software must be scalable: performance should increase proportionally to the number of all ...

EPFL2017

Locking Made Easy

Rachid Guerraoui, Vasileios Trigonakis, Georgios Chatzopoulos

A priori, locking seems easy: To protect shared data from concurrent accesses, it is sufficient to lock before accessing the data and unlock after. Nevertheless, making locking efficient requires fine-tuning (a) the granularity of locks and (b) the locking ...

ACM Press2016

Safety, Liveness and Parallelism in Concurrent Computing

Victor Bushkov

The correctness of a shared object, which can be accessed by several processes concurrently, is specified through two different kinds of properties - safety and liveness. When implementing a shared object it is important to specify its correctness in a suc ...

EPFL2015

Composing Relaxed Transactions

Rachid Guerraoui, Vincent Gramoli, Mihai Letia

As the classic transactional abstraction is sometimes considered too restrictive in leveraging parallelism, a lot of work has been devoted to devising relaxed transactional models with the goal of improving concurrency. Nevertheless, the quest for improvin ...

IEEE Computer Society2013

Scalability of write-ahead logging on multicore and multisocket hardware

Anastasia Ailamaki, Frederick Ryan Johnson, Ippokratis Pandis, Radu Ioan Stoica, Manoussos Gavriil Athanassoulis

The shift to multi-core and multi-socket hardware brings new challenges to database systems, as the software parallelism determines performance. Even though database systems traditionally accommodate simultaneous requests, a multitude of synchronization ba ...

2012

Speculative Linearizability

Rachid Guerraoui, Viktor Kuncak, Giuliano Losa

Linearizability is a key design methodology for reasoning about implementations of concurrent abstract data types in both shared memory and message passing systems. It provides the illusion that operations execute sequentially and fault-free, despite the a ...

Assoc Computing Machinery2012

Deadlock Immunity : Enabling General-Purpose Software to Defend Itself against Deadlocks

Horatiu Jula

Deadlock immunity is a property by which programs, once afflicted by a deadlock, develop resistance against future occurrences of that deadlock. We enable real applications to automatically achieve immunity against deadlock bugs involving mutex locks, sema ...

EPFL2011

Aether: A scalable approach to logging

Anastasia Ailamaki, Frederick Ryan Johnson, Ippokratis Pandis, Radu Ioan Stoica, Manoussos Gavriil Athanassoulis

The shift to multi-core hardware brings new challenges to database systems, as the software parallelism determines performance. Even though database systems traditionally accommodate simultaneous requests, a multitude of synchronization barriers serialize ...

2010

Preventing versus Curing: Avoiding Conflicts in Transactional Memories

Rachid Guerraoui, Aleksandar Dragojevic

Transactional memories are typically speculative and rely on contention managers to cure conflicts. This paper explores a complementary approach that prevents conflicts by scheduling transactions according to predictions on their access sets. We first expl ...

2009

Improving OLTP Scalability Using Speculative Lock Inheritance

Anastasia Ailamaki, Frederick Ryan Johnson, Ippokratis Pandis

Transaction processing workloads provide ample request level concurrency which highly parallel architectures can exploit. However, the resulting heavy utilization of core database services also causes resource contention within the database engine itself a ...

2009

Completeness and Nondeterminism in Model Checking Transactional Memories

Rachid Guerraoui

Software transactional memory (STM) offers a disciplined concurrent programming model for exploiting the parallelism of modern processor architectures. This paper presents the first \emph{deterministic} specification automata for strict serializability and ...

Springer2008

Completeness and Nondeterminism in Model Checking Transactional Memories

Rachid Guerraoui

Software transactional memory (STM) offers a disciplined concurrent programming model for exploiting the parallelism of modern processor architectures. This paper presents the first deterministic specification automata for strict serializability and opacit ...

2008

On the Correctness of Transactional Memory

Rachid Guerraoui

Transactional memory (TM) is perceived as an appealing alternative to critical sections for general purpose concurrent programming. Despite the large amount of recent work on TM implementations, however, very little effort has been devoted to precisely def ...

2008