Concurrent objects form the foundation of many applications that exploit multicore architectures and their importance has lead to informal correctness arguments, as well as formal proof systems. Correctness arguments (as found in the distributed computing literature) give intuitive descriptions of a few canonical executions or “scenarios” often each with only a few threads, yet it remains unknown as to whether these intuitive arguments have a formal grounding and extend to arbitrary interleavings over unboundedly many threads.
We present a novel proof technique for concurrent objects, based around identifying a small set of scenarios (representative, canonical interleavings), formalized as the commutativity quotient of a concurrent object. We next give an expression language for defining abstractions of the quotient in the form of regular or context-free languages that enable simple proofs of linearizability. These quotient expressions organize unbounded interleavings into a form more amenable to reasoning and make explicit the relationship between implementation-level contention/interference and ADT-level transitions.
We evaluate our work on numerous non-trivial concurrent objects from the literature (including the Michael-Scott queue, Elimination stack, SLS reservation queue, RDCSS and Herlihy-Wing queue). We show that quotients capture the diverse features/complexities of these algorithms, can be used even when linearization points are not straight-forward, correspond to original authors’ correctness arguments, and provide some new scenario-based arguments. Finally, we show that discovery of some object’s quotients reduces to two-thread reasoning and give an implementation that can derive candidate quotients expressions from source code.
Thu 24 OctDisplayed time zone: Pacific Time (US & Canada) change
16:00 - 17:40 | |||
16:00 20mTalk | Concurrent Data Structures Made Easy OOPSLA 2024 Callista Le Yale-NUS College, Kiran Gopinathan National University of Singapore, Lee Koon Wen Ahrefs, Seth Gilbert National University of Singapore, Ilya Sergey National University of Singapore DOI | ||
16:20 20mTalk | Automated Verification of Parametric Channel-Based Process Communication OOPSLA 2024 Georgian-Vlad Saioc Aarhus University, Julien Lange Royal Holloway, University of London, Anders Møller Aarhus University DOI | ||
16:40 20mTalk | Automated Robustness Verification of Concurrent Data Structure Libraries Against Relaxed Memory Models OOPSLA 2024 Kartik Nagar IIT Madras, Anmol Sahoo Purdue University, Romit Roy Chowdhury Chennai Mathematical Institute, Suresh Jagannathan Purdue University DOI | ||
17:00 20mTalk | Verified Lock-Free Session Channels with Linking OOPSLA 2024 DOI | ||
17:20 20mTalk | Scenario-based Proofs for Concurrent ObjectsRemote OOPSLA 2024 DOI |