Denis Caromel1 Troisieme partie Cours EJC 2003, AUSSOIS, Denis Caromel OASIS Team INRIA -- CNRS - I3S -- Univ. of Nice Sophia-Antipolis EJCP, Lundi 2 juin 2003 ASP: Asynchronous Sequential Processes An Imperative and Parallel Object Calculus

Denis Caromel2 The ASP calculus: Asynchronous Sequential Processes Together with Ludovic Henrio, and Bernard Serpette Objectives: Formally study the ProActive model Investigate various strategies for asynchronous calls Prove some equivalence between Sequential and Parallel programs Demonstrate the deterministic nature of sub-sets of the model

Denis Caromel3 ASP principles and Sequential Calculus Imperative sigma-calculus a la Abadi-Cardelli Sequential Language: Example: a point object A call to a point:

Denis Caromel4 Principles of Reduction

Denis Caromel5 The Heap -- Store Reduced objects: all fields are reduced to a location Heap Reference: Locations Heap Sequential Configuration Heap Well Formed properties

Denis Caromel6 Reduction Context From A. D. Gordon, P. D. Hankin, and S. B. Lassen, Compilation Equivalence of Imperative Objects, FST+TCS’97, LNCS Reduction context = an expression with a hole : provides a deterministic order of evaluation: Target object before parameters Fields of objects: left to right Assignment: left before right Abbreviation of substitution

Denis Caromel7 Sequential Transition System

Denis Caromel8 Sequential TS Properties From Gordon-Hankin-Lassen: Sequential reduction preserves well-formdness: Sequential reduction is deterministic (modulo renaming):

Denis Caromel9 Parallel calculus Language: Intuitive semantics: Object activation: copy together with a deep copy of its reachable objects Asynchronous calls: a Request Queue per Activity M is a list of method labels (names) used to specify the request to be served A list of already computed futures per activity At any time, a full or partial reply may be send back (not eager)

Denis Caromel10 Parallel Binary Tree

Denis Caromel11 Example of a parallel configuration

Denis Caromel12 Structure of Activities (3) Parallel configurations: name of activity [ a current expression being evaluated its own heap a reference towards the Active Object in the heap (root) a list of request to execute in FIFO order: a list of futures already computed (future Id --> obj in heap) A current future: Id associated to the current service

Denis Caromel13 3 additions to the Sequential Calculus In the store: Remote Objects (proxy) and Futures (proxy for futures) Reduction contexts: to reduce within an Active expression

Denis Caromel14 Deep (Parallel) Copy Basic ideas: upon an active object OA(alpha), or a future Fut(f beta->alpha ) the parallel copy stops copying, but pass the OA or Fut as is It means we pass futures as parameters of communications Transition System: Deep Copy (more operational def. exists)

Denis Caromel15 Parallel Transition System

Denis Caromel16 Properties The PTS is correct with respect to the well formed properties:

Denis Caromel17 Store partitioning

Denis Caromel18 A confluence property (1)

Denis Caromel19 A confluence property (2)

Denis Caromel20 A confluence property (3)

Denis Caromel21 A confluence property (4)

Denis Caromel22 A confluence property (5)

Denis Caromel23 Deterministic Object Networks (1)

Denis Caromel24 Deterministic Object Networks (2)

Denis Caromel25 Tree Topology Determinism

Denis Caromel26 Conclusion A library:ProActive 100% Java Parallelism, distribution, synchronization (CSCW), and mobility Reuse -- seamless Polymorphism with existing class types Asynchrony -- Wait-by-necessity An interactive tool towards Metacomputing: IC2D A calculus:ASP: Asynchronous Sequential Processes Capture the semantics, and demonstrates the independence of activities Results of confluence and determinism Mobility to be added ProActive vs. RMI alone : - 30% of code