HVMTP: A time predictable and portable java virtual machine for hard real-time embedded systems

We present HVMTP, a time predictable and portable Java virtual machine (JVM) implementation with applications in resource-constrained, hard real-time embedded systems, which implements all levels of the safety critical Java (SCJ) specification. Time predictability is achieved by a combination of time-predictable algorithms, exploiting the programming model of the SCJ profile and harnessing static knowledge of the hosted SCJ system. This paper presents HVMTP in terms of its design and capabilities and demonstrates how a complete timing model of the JVM represented as a network of timed automata can be obtained using the tool TETASARTSJVM. The timing model readily integrates with the rest of the TETASARTS tool set for temporal verification of SCJ systems. We will also show how a complete timing scheme in terms of safe worst-case execution times and best-case execution times of the Java bytecodes can be derived from the model. Furthermore, we take a first look at how to support the new Java 8 language feature of Lambda expressions in a SCJ context – we look in particular at how the invokedynamic bytecode can be implemented in a time-predictable way and integrated in HVMTP.