Principles of Transactional Memory

194 Pages·2010·1.462 MB·English

by  Rachid Guerraoui, Michal Kapalka

Principles of
Transactional Memory

Synthesis Lectures on
Distributed Computing
Editor
NancyLynch,MassachusettsIntituteofTechnology
SynthesisLecturesonDistributedComputingTheoryiseditedbyNancyLynchoftheMassachusetts
InstituteofTechnology.Theserieswillpublish50-to150pagepublicationsontopicspertainingto
distributedcomputingtheory.Thescopewilllargelyfollowthepurviewofpremierinformationand
computerscienceconferences,suchasACMPODC,DISC,SPAA,OPODIS,CONCUR,
DialM-POMC,ICDCS,SODA,Sirocco,SSS,andrelatedconferences.Potentialtopicsinclude,but
notarelimitedto:distributedalgorithmsandlowerbounds,algorithmdesignmethods,formal
modelingandverificationofdistributedalgorithms,andconcurrentdatastructures.
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2010
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Copyright© 2010byMorgan&Claypool
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PrinciplesofTransactionalMemory
RachidGuerraouiandMichałKapałka
www.morganclaypool.com
ISBN:9781608450114 paperback
ISBN:9781608450121 ebook
DOI10.2200/S00253ED1V01Y201009DCT004
APublicationintheMorgan&ClaypoolPublishersseries
SYNTHESISLECTURESONDISTRIBUTEDCOMPUTING
Lecture#4
SeriesEditor:NancyLynch,MassachusettsIntituteofTechnology
SeriesISSN
SynthesisLecturesonDistributedComputing
Print2155-1626 Electronic2155-1634
Principles of
Transactional Memory
Rachid Guerraoui and Michał Kapałka
ÉcolePolytechniqueFédéraledeLausanne
SYNTHESISLECTURESONDISTRIBUTEDCOMPUTING#4
M
&C Morgan &cLaypool publishers
ABSTRACT
Transactionalmemory(TM)isanappealingparadigmforconcurrentprogrammingonsharedmemory
architectures.With aTM,threads of an application communicate,and synchronize their actions,
viain-memorytransactions.Eachtransactioncanperformanynumberofoperationsonshareddata,
and then either commit or abort. When the transaction commits, the effects of all its operations
becomeimmediatelyvisibletoothertransactions;whenitaborts,however,thoseeffectsareentirely
discarded.Transactionsareatomic:programmersgettheillusionthateverytransactionexecutesall
itsoperationsinstantaneously,atsomesingleanduniquepointintime.Yet,aTMrunstransactions
concurrentlytoleveragetheparallelismofferedbymodernprocessors.
The aim of this book is to provide theoretical foundations for transactional memory.This
includes defining a model of aTM,as well as answering precisely when aTM implementation is
correct,whatkindofpropertiesitcanensure,whatarethepowerandlimitationsofaTM,andwhat
inherenttrade-offsareinvolvedindesigningaTMalgorithm.Whilethefocusofthisbookisonthe
fundamental principles,its goal is to capture the common intuition behind the semantics ofTMs
andthepropertiesofexistingTMimplementations.
KEYWORDS
transactionalmemory,concurrentprogramming,sharedmemory,theory
To Anne.
To Agnieszka and Artur.

ix
Contents
Acknowledgments.......................................................xiii
1 Introduction ..............................................................1
1.1 ProblemswithExplicitLocking .......................................... 1
1.2 TransactionalMemory .................................................. 3
1.3 ScopeofthisBook...................................................... 4
1.4 Contents .............................................................. 5
PARTI Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 SharedMemorySystems ...................................................9
2.1 BasicAbstractions ...................................................... 9
2.1.1 ProcessesandSharedObjects ...................................... 9
2.1.2 SharedObjectImplementations ................................... 10
2.1.3 ExecutionsofConcurrentAlgorithms .............................. 11
2.1.4 Histories ....................................................... 13
2.1.5 SemanticsofBaseObjects ........................................ 15
2.1.6 ConfigurationsandIndistinguishability ............................. 17
2.1.7 AsynchronyandWait-Freedom.................................... 18
2.1.8 ComputabilityQuestions ......................................... 19
2.2 SummaryofNotation .................................................. 20
3 TransactionalMemory:APrimer.......................................... 23
3.1 TMSharedObject..................................................... 23
3.1.1 Transactions .................................................... 24
3.1.2 T-ObjectsandtheirSemantics .................................... 25
3.2 TMHistories ......................................................... 27
3.2.1 StatusofTransactions ............................................ 27
3.2.2 Real-TimeOrder ................................................ 28
3.2.3 Conflicts ....................................................... 28