Abstract This paper describes JaRec, a portable record/replay system for Java. It correctly replays multi‐threaded, data‐race free Java applications, by recording the order of synchronization operations, and by executing them in the same order during replay. The record/replay infrastructure is developed in Java, and does not require a modification of the Java Virtual Machine (JVM) if it provides the JVM Profiler Interface (JVMPI). If the JVM does not support JVMPI, which is used for intercepting the loaded classes, only a minor modification to the JVM is required in order to run the system. On ystems with limited memory resources, JaRec can be executed in a distributed fashion. This also makes it suitable to aid debugging of multi‐threaded applications on embedded systems. Copyright © 2004 John Wiley & Sons, Ltd.

This article presents a practical solution for the cyclic debugging of nondeterministic parallel programs. The solution consists of a combination of record/replay with automatic on-the-fly data race detection. This combination enables us to limit the record phase to the more efficient recording of the synchronization operations, while deferring the time-consuming data race detection to the replay phase. As the record phase is highly efficient, there is no need to switch it off, hereby eliminating the possibility of Heisenbugs because tracing can be left on all the time. This article describes an implementation of the tools needed to support RecPlay.