ICFP 2022
Sun 11 - Fri 16 September 2022 Ljubljana, Slovenia
Mon 12 Sep 2022 14:00 - 14:20 at Linhart - Analysis and Transformations Chair(s): Malgorzata Biernacka

Recent research on parallel functional programming has culminated in a provably efficient (in work and space) parallel memory manager, which has been incorporated into the MPL (MaPLe) compiler for Parallel ML and shown to deliver practical efficiency and scalability. The memory manager exploits a property of parallel programs called disentanglement, which restricts computations from accessing concurrently allocated objects. Disentanglement is closely related to race-freedom, but subtly differs from it. Unlike race-freedom, however, no known techniques exists for ensuring disentanglement, leaving the task entirely to the programmer. This is a challenging task, because it requires reasoning about low-level memory operations (e.g., allocations and accesses), which is especially difficult in functional languages.

In this paper, we present techniques for detecting entanglement dynamically, while the program is running. We first present a dynamic semantics for a functional language with references that checks for entanglement by consulting parallel and sequential dependency relations in the program. Notably, the semantics requires checks for mutable objects only. We prove the soundness of the dynamic semantics and present several techniques for realizing it efficiently, in particular by pruning away a large number of entanglement checks. We also provide bounds on the work and space of our techniques.

We show that the entanglement detection techniques are practical by implementing them in the MPL compiler for Parallel ML. Considering a variety of benchmarks, we present an evaluation and measure time and space overheads of less than 5% on average with up to 72 cores. These results show that entanglement detection has negligible cost and can therefore remain deployed with little or no impact on efficiency, scalability, and space.

Mon 12 Sep

Displayed time zone: Belgrade, Bratislava, Budapest, Ljubljana, Prague change

13:40 - 15:20
Analysis and TransformationsICFP Papers and Events at Linhart
Chair(s): Malgorzata Biernacka University of Wrocław
13:40
20m
Talk
Reference Counting with Frame Limited Reuse
ICFP Papers and Events
Anton Lorenzen University of Bonn, Daan Leijen Microsoft Research
DOI
14:00
20m
Talk
Entanglement Detection With Near-Zero CostDistinguished Paper
ICFP Papers and Events
Sam Westrick Carnegie Mellon University, Jatin Arora Carnegie Mellon University, Umut A. Acar Carnegie Mellon University
DOI
14:20
20m
Talk
Generating circuits with generators
ICFP Papers and Events
Marek Materzok University of Wroclaw
DOI
14:40
20m
Talk
Staged Compilation With Two-Level Type Theory
ICFP Papers and Events
András Kovács Eötvös Loránd University
DOI
15:00
20m
Talk
Random Testing of a Higher-Order Blockchain LanguageExperience Report
ICFP Papers and Events
Tram Hoang National University of Singapore, Anton Trunov Zilliqa Research, Leonidas Lampropoulos University of Maryland, College Park, Ilya Sergey National University of Singapore
DOI Pre-print