TY - JOUR
T1 - Safe privatization in transactional memory
AU - Khyzha, Artem
AU - Attiya, Hagit
AU - Gotsman, Alexey
AU - Rinetzky, Noam
N1 - Publisher Copyright:
© 2018 ACM.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2018/2/10
Y1 - 2018/2/10
N2 - Transactional memory (TM) facilitates the development of concurrent applications by letting the programmer designate certain code blocks as atomic. Programmers using a TM often would like to access the same data both inside and outside transactions, e.g., to improve performance or to support legacy code. In this case, programmers would ideally like the TM to guarantee strong atomicity, where transactions can be viewed as executing atomically also with respect to non-transactional accesses. Since guaranteeing strong atomicity for arbitrary programs is prohibitively expensive, researchers have suggested guaranteeing it only for certain data-race free (DRF) programs, particularly those that follow the privatization idiom: from some point on, threads agree that a given object can be accessed non-transactionally. Supporting privatization safely in a TM is nontrivial, because this often requires correctly inserting transactional fences, which wait until all active transactions complete. Unfortunately, there is currently no consensus on a single definition of transactional DRF, in particular, because no existing notion of DRF takes into account transactional fences. In this paper we propose such a notion and prove that, if a TM satisfies a certain condition generalizing opacity and a program using it is DRF assuming strong atomicity, then the program indeed has strongly atomic semantics. We show that our DRF notion allows the programmer to use privatization idioms. We also propose a method for proving our generalization of opacity and apply it to the TL2 TM.
AB - Transactional memory (TM) facilitates the development of concurrent applications by letting the programmer designate certain code blocks as atomic. Programmers using a TM often would like to access the same data both inside and outside transactions, e.g., to improve performance or to support legacy code. In this case, programmers would ideally like the TM to guarantee strong atomicity, where transactions can be viewed as executing atomically also with respect to non-transactional accesses. Since guaranteeing strong atomicity for arbitrary programs is prohibitively expensive, researchers have suggested guaranteeing it only for certain data-race free (DRF) programs, particularly those that follow the privatization idiom: from some point on, threads agree that a given object can be accessed non-transactionally. Supporting privatization safely in a TM is nontrivial, because this often requires correctly inserting transactional fences, which wait until all active transactions complete. Unfortunately, there is currently no consensus on a single definition of transactional DRF, in particular, because no existing notion of DRF takes into account transactional fences. In this paper we propose such a notion and prove that, if a TM satisfies a certain condition generalizing opacity and a program using it is DRF assuming strong atomicity, then the program indeed has strongly atomic semantics. We show that our DRF notion allows the programmer to use privatization idioms. We also propose a method for proving our generalization of opacity and apply it to the TL2 TM.
KW - observational refinement
KW - privatization
KW - software transactional memory
KW - strong atomicity
UR - http://www.scopus.com/inward/record.url?scp=85084180310&partnerID=8YFLogxK
U2 - 10.1145/3200691.3178505
DO - 10.1145/3200691.3178505
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AN - SCOPUS:85084180310
SN - 1523-2867
VL - 53
SP - 233
EP - 245
JO - SIGPLAN Notices (ACM Special Interest Group on Programming Languages)
JF - SIGPLAN Notices (ACM Special Interest Group on Programming Languages)
IS - 1
ER -