Service Coroner: A Diagnostic Tool for Locating OSGi Stale References

The OSGi Services Platform provides a framework for the dynamic deployment of Java-based applications. It allows to install, to activate, to update and to uninstall application modules without the need to restart the host Java Virtual Machine. However, the mishandling of such OSGi dynamics may result in a problem described in the OSGi specification as Stale References, which happen when services from uninstalled modules are still referenced by active code. It may lead to inconsistencies in application´s behavior, state and memory. Currently, there are no tools available to address this issue. This paper presents a diagnostics tool named ServiceCoroner that detects such problems. It helps developers and administrators diagnose OSGi applications running either in production or test environments. We have validated this tool on two open source applications that run on OSGi: a JavaEE application server and a multi-protocol instant messenger application. The results of the experiments show stale references in those applications.