Long-Lived Tasks

  • Armando Castañeda
  • Sergio Rajsbaum
  • Michel Raynal
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10299)


The predominant notion for specifying problems to study distributed computability are tasks. Notable examples of tasks are consensus, set agreement, renaming and commit-adopt. The theory of task solvability is well-developed using topology techniques and distributed simulations. However, concurrent computing problems are usually specified by objects. Tasks and objects differ in at least two ways. While a task is a one-shot problem, an object, such as a queue or a stack, typically can be invoked multiple times by each process. Also, a task, defined in terms of sets, specifies its responses when invoked by each set of processes concurrently, while an object, defined in terms of sequences, specifies the outputs the object may produce when it is accessed sequentially.

In a previous paper we showed how tasks can be used to specify one-shot objects (where each process can invoke only one operation, only once). In this paper we show how the notion of tasks can be extended to model any object. A potential benefit of this result is the use of topology, and other distributed computability techniques to study long-lived objects.


Distributed problems Formal specifications Tasks Sequential specifications Linearizability Long-lived objects 



Armando Castañeda was supported by UNAM-PAPIIT project IA102417. Sergio Rajsbaum was supported by UNAM-PAPIIT project IN109917. Part of this work was done while Sergio Rajsbaum was at École Polytechnique and Paris 7 University. Michel Raynal was supported the French ANR project DESCARTES (grant 16-CE40-0023-03) devoted to distributed software engineering. This work was also partly supported by the INRIA-UNAM Équipe Associée LiDiCo (at the Limits of Distributed Computing).


  1. 1.
    Borowsky, E., Gafni, E.: Immediate atomic snapshots and fast renaming. In: Proceedings of the 12th ACM Symposium on Principles of Distributed Computing (PODC 1993), pp. 41–51. ACM Press (1993)Google Scholar
  2. 2.
    Borowsky, E., Gafni, E., Lynch, N., Rajsbaum, S.: The BG distributed simulation algorithm. Distrib. Comput. 14(3), 127–146 (2001)CrossRefGoogle Scholar
  3. 3.
    Chandra, T.D., Hadzilacos, V., Jayanti, P., Toueg, S.: Generalized irreducibility of consensus and the equivalence of \(t\)-resilient and wait-free implementations of consensus. SIAM J. Comput. 34(2), 333–357 (2004)MathSciNetCrossRefMATHGoogle Scholar
  4. 4.
    Castañeda, A., Rajsbaum, S., Raynal, M.: Specifying concurrent problems: beyond linearizability and up to tasks. In: Moses, Y. (ed.) DISC 2015. LNCS, vol. 9363, pp. 420–435. Springer, Heidelberg (2015). doi: 10.1007/978-3-662-48653-5_28 CrossRefGoogle Scholar
  5. 5.
    Friedman, R., Vitenberg, R., Chokler, G.: On the composability of consistency conditions. Inf. Process. Lett. 86(4), 169–176 (2003)MathSciNetCrossRefMATHGoogle Scholar
  6. 6.
    Gafni, E.: Snapshot for time: the one-shot case, 10 pages (2014). arXiv:1408.3432v1
  7. 7.
    Herlihy, M., Kozlov, D., Rajsbaum, S.: Distributed Computing Through Combinatorial Topology, 336 pages. Morgan Kaufmann/Elsevier (2014)Google Scholar
  8. 8.
    Herlihy, M., Rajsbaum, S., Raynal, M.: Power and limits of distributed computing shared memory models. Theoret. Comput. Sci. 509, 3–24 (2013)MathSciNetCrossRefMATHGoogle Scholar
  9. 9.
    Hemed, N., Rinetzky, N.: Brief announcement: concurrency-aware linearizability. In: Proceedings of the 33th ACM Symposium on Principles of Distributed Computing (PODC 2014), pp. 209–211. ACM Press (2014)Google Scholar
  10. 10.
    Hemed, N., Rinetzky, N., Vafeiadis, V.: Modular verification of concurrency-aware linearizability. In: Moses, Y. (ed.) DISC 2015. LNCS, vol. 9363, pp. 371–387. Springer, Heidelberg (2015). doi: 10.1007/978-3-662-48653-5_25 CrossRefGoogle Scholar
  11. 11.
    Herlihy, M., Wing, J.: Linearizability: a correctness condition for concurrent objects. ACM Trans. Program. Lang. Syst. 12(3), 463–492 (1990)CrossRefGoogle Scholar
  12. 12.
    Moran, S., Wolfstahl, Y.: Extended impossibility results for asynchronous complete networks. Inf. Process. Lett. 26(3), 145–151 (1987)MathSciNetCrossRefGoogle Scholar
  13. 13.
    Neiger, G.: Set-linearizability. Brief announcement in Proc. 13th ACM Symposium on Principles of Distributed Computing (PODC 1994), p. 396. ACM Press (1994)Google Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Armando Castañeda
    • 1
  • Sergio Rajsbaum
    • 1
  • Michel Raynal
    • 2
    • 3
  1. 1.Instituto de Matemáticas, UNAMMéxico D.FMexico
  2. 2.Institut Universitaire de FranceParisFrance
  3. 3.IRISAUniversité de RennesRennesFrance

Personalised recommendations