Revisiting Deterministic Multithreading Strategies ∗

Deterministic behaviour is a prerequisite for most approaches to object replication. In order to avoid the nondeterminism of multithreading, many object replication systems are limited to using sequential method execution. In this paper, we survey existing application-level scheduling algorithms that enable deterministic concurrent execution of object methods. Multithreading leads to a more efficient execution on multiple CPUs and multi-core CPUs, and it enables the object programmer to use condition variables for coordination between multiple invocations. In existing algorithms, a thread may only start or resume if there are no potentially nondeterministic conflicts with other running threads. A decision only based on past actions, without knowledge of future behaviour, must use a pessimistic strategy that can cause unnecessary restrictions to concurrency. Using a priori knowledge about future actions of a thread allows increasing the concurrency. We propose static code analysis as a way for predicting the lock acquisitions of object methods.