Staccato: A Bug Finder for Dynamic Configuration Updates

Many modern software applications are highly configurable, allowing configuration options to be changed even during program execution. When dynamic configuration updating is implemented incorrectly, program errors can result. These program errors occur primarily when stale data—computed from old configurations—or inconsistent data—computed from different configurations—are used. We introduce Staccato, the first tool designed to detect these errors. Staccato uses a dynamic analysis in the style of taint analysis to find the use of stale or inconsistent configuration data in Java programs. It supports concurrent programs on commodity JVMs. In some cases, Staccato can provide automatic bug avoidance and semi-automatic repair when errors occur. We evaluated Staccato on three open-source applications that support complex reconfigurability. Staccato found multiple errors in all of them. Staccato requires only modest annotation overhead and has moderate performance overhead. 1998 ACM Subject Classification D.2.9; Software configuration management