Title
Single global lock semantics in a weakly atomic STM
Abstract
As memory transactions have been proposed as a language-level replacement for locks, there is growing need for well-defined semantics. In contrast to database transactions, transaction memory (TM) semantics are complicated by the fact that programs may access the same memory locations both inside and outside transactions. Strongly atomic semantics, where non-transactional accesses are treated as implicit single-operation transactions, remain difficult to provide without specialized hardware support and/or significant performance overhead. As an alternative, many in the community have informally proposed that a single global lock semantics [16, 9], where transaction semantics are mapped to those of regions protected by a single global lock, provide an intuitive and efficiently implementable model for programmers. In this paper, we explore the implementation and performance implications of single global lock semantics in a weakly atomic STM from the perspective of Java, and we discuss why even recent STM implementations fall short of these semantics. We describe a new weakly atomic Java STM implementation that provides single global lock semantics while permitting concurrent execution, but we show that this comes at a significant performance cost. We also propose and implement various alternative semantics that loosen single lock requirements while still providing strong guarantees. We compare our new implementations to previous ones, including a strongly atomic STM. [22]
Year
DOI
Venue
2008
10.1145/1402227.1402235
SIGPLAN Notices
Keywords
Field
DocType
single global lock,new weakly atomic java,stm implementation,single lock requirement,well-defined semantics,transaction semantics,atomic semantics,atomic stm,various alternative semantics,single global lock semantics,weakly atomic stm,transactional memory
Semantic memory,Transaction processing,Programming language,Lock (computer science),Computer science,Concurrency,Parallel computing,Implementation,Database transaction,Java,Semantics
Journal
Volume
Issue
ISSN
43
5
0362-1340
Citations 
PageRank 
References 
19
0.93
14
Authors
7
Name
Order
Citations
PageRank
Vijay Menon119113.11
Steven Balensiefer21074.50
Tatiana Shpeisman343632.69
Ali-Reza Adl-Tabatabai497162.68
Richard L. Hudson558338.03
Bratin Saha674239.04
Adam Welc738424.01