Pickling Threads State in the Java System

Java provides a serialization mechanism which allows the capture and restoration of objects’ state and therefore the migration of objects between machines. It also allows classes to be dynamically loaded and therefore to be moved between nodes. However, Java does not provide a mechanism for capturing and restoring a thread state. The stack of a Java thread is not accessible. Such a mechanism would allow a thread to be checkpointed or migrated between different nodes. In this paper, we report on our experience which consisted in extending the Java virtual machine in order to allow the capture and restoration of a thread state. We describe the principles of the implementation of this extension and provide preliminary results of its evaluation.