Deriving optimal checkpoint protocols for distributed shared memory architectures

Abstract

Uncoordinated checkpointing is one technique used to build processes that can recover to a consistent state after crashing. This technique requires each process to periodically record its state in a checkpoint. Furthermore, the threads executing on each process log any non-deterministic action that they take following the latest checkpointed state. When a process crashes, a new process, initialized with the appropriate recorded local state, is created in its place. The new process restarts executing, and whenever one of its threads confronts a non-deterministic choice, the thread references the log in order to reproduce the same action performed before the crash. Thus, uncoordinated checkpointing implements an abstraction of a resilient process in which the crash of a process is translated into intermittent unavailability of that process.

We give a specification of the consistency property “no orphan threads” in the context of multithreaded processes running on a shared memory multiprocessor. We also give a definition of optimality for uncoordinated checkpointing protocols given a memory coherency protocol. We then use this specification to derive an existing uncoordinated checkpoint protocol and show that it is optimal. This protocol assumes that once a process crashes, no further processes crash until the first process completes recovery.

This author was supported in part by the Office of Naval Research under contract N00014-91-J-1219, the National Science Foundation under Grant No. CCR-9003440, DARPA/NSF Grant No. CCR-9014363, NASA/DARPA grant NAG-2-893, and AFOSR grant F49620-94-1-0198. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author and do not reflect the views of these agencies.

This author was supported in part by the Defense Advanced Research Projects Agency (DoD) under NASA Ames grant number NAG 2-593, Contract N00140-87-C-8904 and by AFOSR grant number F49620-93-1-0242. The views, opinions, and findings contained in this report are those of the authors and should not be construed as an official Department of Defense position, policy, or decision.