Runtime Verification of Kotlin Coroutines

Abstract

Kotlin was introduced to Android as the recommended language for development. One of the unique functionalities of Kotlin is that of coroutines, which are lightweight tasks that can run concurrently inside threads. Programming using coroutines is difficult, among other things, because they can move between threads and behave unexpectedly. We introduce runtime verification in Kotlin. We provide a language to write properties and produce runtime monitors tailored to verify Kotlin coroutines. We identify, formalise and runtime verify seven properties about common runtime errors that are not easily identifiable by static analysis. To demonstrate the acceptability of the technique in real applications, we apply our framework to an in-house Android app and micro-benchmarks and measure the execution time and memory overheads.