CCCP

摘要

Calling context profiling is an important technique for locating hotspots in programs. The prevailing data structure is the Calling Context Tree (CCT) that provides dynamic metrics for each calling context. Existing approaches to calling context profiling in Java either limit portability due to the use of native code or of a modified Java Virtual Machine, create incomplete and inaccurate CCTs, or cause excessive overhead. In this paper, we introduce Complete Calling Context Profiling (CCCP), a new approach that reconciles completeness and accuracy of the created CCTs, portability, and moderate overhead. CCCP relies on a generic bytecode instrumentation framework ensuring comprehensive bytecode coverage, including also the standard Java class library. In order to reduce the overhead of accessing the current CCT node, CCCP transforms code such that the caller passes its CCT node to the callee as a special method argument, while ensuring compatibility with native code, reflection, and stack introspection. We use the resulting CCTs for a detailed analysis of the dynamic behavior of Java systems and present a thorough analysis of the origin of runtime overheads.