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.KeywordsShared MemoryState IntervalShared Memory SystemRead EventShared Memory MultiprocessorThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.