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Documents authored by Johnsen, Einar Broch

Document
DOI: 10.4230/LIPIcs.CONCUR.2023.9
Compositional Correctness and Completeness for Symbolic Partial Order Reduction

Authors: Åsmund Aqissiaq Arild Kløvstad, Eduard Kamburjan, and Einar Broch Johnsen

Published in: LIPIcs, Volume 279, 34th International Conference on Concurrency Theory (CONCUR 2023)

Abstract
Partial Order Reduction (POR) and Symbolic Execution (SE) are two fundamental abstraction techniques in program analysis. SE is particularly useful as a state abstraction technique for sequential programs, while POR addresses equivalent interleavings in the execution of concurrent programs. Recently, several promising connections between these two approaches have been investigated, which result in symbolic partial order reduction: partial order reduction of symbolically executed programs. In this work, we provide compositional notions of completeness and correctness for symbolic partial order reduction. We formalize completeness and correctness for (1) abstraction over program states and (2) trace equivalence, such that the abstraction gives rise to a complete and correct SE, the trace equivalence gives rise to a complete and correct POR, and their combination results in complete and correct symbolic partial order reduction. We develop our results for a core parallel imperative programming language and mechanize the proofs in Coq.
Cite as

Åsmund Aqissiaq Arild Kløvstad, Eduard Kamburjan, and Einar Broch Johnsen. Compositional Correctness and Completeness for Symbolic Partial Order Reduction. In 34th International Conference on Concurrency Theory (CONCUR 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 279, pp. 9:1-9:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{klvstad_et_al:LIPIcs.CONCUR.2023.9,
  author =	{Kl{\o}vstad, \r{A}smund Aqissiaq Arild and Kamburjan, Eduard and Johnsen, Einar Broch},
  title =	{{Compositional Correctness and Completeness for Symbolic Partial Order Reduction}},
  booktitle =	{34th International Conference on Concurrency Theory (CONCUR 2023)},
  pages =	{9:1--9:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-299-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{279},
  editor =	{P\'{e}rez, Guillermo A. and Raskin, Jean-Fran\c{c}ois},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2023.9},
  URN =		{urn:nbn:de:0030-drops-190035},
  doi =		{10.4230/LIPIcs.CONCUR.2023.9},
  annote =	{Keywords: Symbolic Execution, Coq, Trace Semantics, Partial Order Reduction}
}
Document
DOI: 10.4230/OASIcs.Gabbrielli.10
Inseguendo Fagiani Selvatici: Partial Order Reduction for Guarded Command Languages

Authors: Frank S. de Boer, Einar Broch Johnsen, Rudolf Schlatte, Silvia Lizeth Tapia Tarifa, and Lars Tveito

Published in: OASIcs, Volume 86, Recent Developments in the Design and Implementation of Programming Languages (2020)

Abstract
This paper presents a method for testing whether objects in actor languages and active object languages exhibit locally deterministic behavior. We investigate such a method for a class of guarded command programs, abstracting from object-oriented features like method calls but focusing on cooperative scheduling of dynamically spawned processes executing in parallel. The proposed method can answer questions such as whether all permutations of an execution trace are equivalent, by generating candidate traces for testing which may lead to different final states. To prune the set of candidate traces, we employ partial order reduction. To further reduce the set, we introduce an analysis technique to decide whether a generated trace is schedulable. Schedulability cannot be decided for guarded commands using standard dependence and interference relations because guard enabledness is non-monotonic. To solve this problem, we use concolic execution to produce linearized symbolic traces of the executed program, which allows a weakest precondition computation to decide on the satisfiability of guards.
Cite as

Frank S. de Boer, Einar Broch Johnsen, Rudolf Schlatte, Silvia Lizeth Tapia Tarifa, and Lars Tveito. Inseguendo Fagiani Selvatici: Partial Order Reduction for Guarded Command Languages. In Recent Developments in the Design and Implementation of Programming Languages. Open Access Series in Informatics (OASIcs), Volume 86, pp. 10:1-10:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{deboer_et_al:OASIcs.Gabbrielli.10,
  author =	{de Boer, Frank S. and Johnsen, Einar Broch and Schlatte, Rudolf and Tapia Tarifa, Silvia Lizeth and Tveito, Lars},
  title =	{{Inseguendo Fagiani Selvatici: Partial Order Reduction for Guarded Command Languages}},
  booktitle =	{Recent Developments in the Design and Implementation of Programming Languages},
  pages =	{10:1--10:18},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-171-9},
  ISSN =	{2190-6807},
  year =	{2020},
  volume =	{86},
  editor =	{de Boer, Frank S. and Mauro, Jacopo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.Gabbrielli.10},
  URN =		{urn:nbn:de:0030-drops-132322},
  doi =		{10.4230/OASIcs.Gabbrielli.10},
  annote =	{Keywords: Testing, Symbolic Traces, Guarded Commands, Partial Order Reduction}
}
Document
Artifact
DOI: 10.4230/DARTS.5.2.1
Godot: All the Benefits of Implicit and Explicit Futures (Artifact)

Authors: Kiko Fernandez-Reyes, Dave Clarke, Ludovic Henrio, Einar Broch Johnsen, and Tobias Wrigstad

Published in: DARTS, Volume 5, Issue 2, Special Issue of the 33rd European Conference on Object-Oriented Programming (ECOOP 2019)

Abstract
This artifact contains an implementation of data-flow futures in terms of control-flow futures, in the Scala language. In the implementation, we show microbenchmarks that solve the three identified problems from the paper: 1) The Type Proliferation Problem, 2) The Fulfilment Observation Problem, and 3) The Future Proliferation Problem There are also detailed instructions on design decisions that differ from the formal semantics and restrictions on the limits of how much can be encoded in the Scala language. We provide examples, e.g., creation of a proxy service using data-flow futures, as well as tests that exercise different parts of the type system.
Cite as

Kiko Fernandez-Reyes, Dave Clarke, Ludovic Henrio, Einar Broch Johnsen, and Tobias Wrigstad. Godot: All the Benefits of Implicit and Explicit Futures (Artifact). In Special Issue of the 33rd European Conference on Object-Oriented Programming (ECOOP 2019). Dagstuhl Artifacts Series (DARTS), Volume 5, Issue 2, pp. 1:1-1:2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@Article{fernandezreyes_et_al:DARTS.5.2.1,
  author =	{Fernandez-Reyes, Kiko and Clarke, Dave and Henrio, Ludovic and Johnsen, Einar Broch and Wrigstad, Tobias},
  title =	{{Godot: All the Benefits of Implicit and Explicit Futures}},
  pages =	{1:1--1:2},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2019},
  volume =	{5},
  number =	{2},
  editor =	{Fernandez-Reyes, Kiko and Clarke, Dave and Henrio, Ludovic and Johnsen, Einar Broch and Wrigstad, Tobias},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.5.2.1},
  URN =		{urn:nbn:de:0030-drops-107786},
  doi =		{10.4230/DARTS.5.2.1},
  annote =	{Keywords: Futures, Concurrency, Type Systems, Formal Semantics}
}
Document
DOI: 10.4230/LIPIcs.ECOOP.2019.2
Godot: All the Benefits of Implicit and Explicit Futures

Authors: Kiko Fernandez-Reyes, Dave Clarke, Ludovic Henrio, Einar Broch Johnsen, and Tobias Wrigstad

Published in: LIPIcs, Volume 134, 33rd European Conference on Object-Oriented Programming (ECOOP 2019)

Abstract
Concurrent programs often make use of futures, handles to the results of asynchronous operations. Futures provide means to communicate not yet computed results, and simplify the implementation of operations that synchronise on the result of such asynchronous operations. Futures can be characterised as implicit or explicit, depending on the typing discipline used to type them. Current future implementations suffer from "future proliferation", either at the type-level or at run-time. The former adds future type wrappers, which hinders subtype polymorphism and exposes the client to the internal asynchronous communication architecture. The latter increases latency, by traversing nested future structures at run-time. Many languages suffer both kinds. Previous work offer partial solutions to the future proliferation problems; in this paper we show how these solutions can be integrated in an elegant and coherent way, which is more expressive than either system in isolation. We describe our proposal formally, and state and prove its key properties, in two related calculi, based on the two possible families of future constructs (data-flow futures and control-flow futures). The former relies on static type information to avoid unwanted future creation, and the latter uses an algebraic data type with dynamic checks. We also discuss how to implement our new system efficiently.
Cite as

Kiko Fernandez-Reyes, Dave Clarke, Ludovic Henrio, Einar Broch Johnsen, and Tobias Wrigstad. Godot: All the Benefits of Implicit and Explicit Futures. In 33rd European Conference on Object-Oriented Programming (ECOOP 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 134, pp. 2:1-2:28, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{fernandezreyes_et_al:LIPIcs.ECOOP.2019.2,
  author =	{Fernandez-Reyes, Kiko and Clarke, Dave and Henrio, Ludovic and Johnsen, Einar Broch and Wrigstad, Tobias},
  title =	{{Godot: All the Benefits of Implicit and Explicit Futures}},
  booktitle =	{33rd European Conference on Object-Oriented Programming (ECOOP 2019)},
  pages =	{2:1--2:28},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-111-5},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{134},
  editor =	{Donaldson, Alastair F.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2019.2},
  URN =		{urn:nbn:de:0030-drops-107949},
  doi =		{10.4230/LIPIcs.ECOOP.2019.2},
  annote =	{Keywords: Futures, Concurrency, Type Systems, Formal Semantics}
}
Document
DOI: 10.4230/DagSemProc.09301.3
Minimal Ownership for Active Objects

Authors: David Clarke, Tobias Wrigstad, Johan Ostlund, and Einar Broch Johnsen

Published in: Dagstuhl Seminar Proceedings, Volume 9301, Typing, Analysis and Verification of Heap-Manipulating Programs (2010)

Abstract
Active objects offer a structured approach to concurrency, encapsulating both unshared state and a thread of control. For efficient data transfer, data should be passed by reference whenever possible, but this introduces aliasing and undermines the validity of the active objects. This paper proposes a minimal variant of ownership types that preserves the required race freedom invariant yet enables data transfer by reference between active objects (that is, without copying) in many cases, and a cheap clone operation where copying is necessary. Our approach is general and should be adaptable to several existing active object systems.
Cite as

David Clarke, Tobias Wrigstad, Johan Ostlund, and Einar Broch Johnsen. Minimal Ownership for Active Objects. In Typing, Analysis and Verification of Heap-Manipulating Programs. Dagstuhl Seminar Proceedings, Volume 9301, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{clarke_et_al:DagSemProc.09301.3,
  author =	{Clarke, David and Wrigstad, Tobias and Ostlund, Johan and Johnsen, Einar Broch},
  title =	{{Minimal Ownership for Active Objects}},
  booktitle =	{Typing, Analysis and Verification of Heap-Manipulating Programs},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{9301},
  editor =	{Peter O'Hearn and Arnd Poetzsch-Heffter and Mooly Sagiv},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.09301.3},
  URN =		{urn:nbn:de:0030-drops-24379},
  doi =		{10.4230/DagSemProc.09301.3},
  annote =	{Keywords: Ownership, concurrency, uniqueness, active objects}
}
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