In 2011, we introduced iterative and incremental A.C.P. root cause analysis methodology. Its name is an abbreviation from the three main constituents: artifacts, checklists, and patterns. We get software execution artifacts such as memory dumps and software logs, use checklists to guide us in our problem analysis efforts, recognize patterns of abnormal software structure and behavior, and ultimately find out root cause(s). Recognized patterns may prompt us to revisit checklists for further guidance and request more software execution artifacts. The process is illustrated in the following diagram:
At that time, pattern-oriented software diagnostics was not yet fully developed so the proposed root cause analysis methodology was primarily debugger commands-based for memory analysis (in the form of checklists) and analysis patterns-based for software trace and log analysis where checklists were patterns-based. Pattern sequences (former pattern succession) help in finding root causes.
With the development of pattern-oriented software diagnostics, we realized the centrality of patterns and the division of patterns into general and concrete problem patterns and problem analysis patterns.
This brought the revision of A.C.P methodology where checklists become attributes of artifact collection and pattern catalogues:
However, the causal nation of root cause analysis is not explicitly mentioned in the process. Many problem patterns can be caused differently, for example, Dynamic Memory Corruption patterns can be caused by buffer overwrites and underwrites, invalid API parameters, double memory releases, and even memory manager defects resulting in similar diagnostic indicators seen in memory snapshots and traces.
Therefore, we introduce the notion of Mechanism to describe the possible cause of a diagnostic pattern. Such mechanisms replace pattern sequences as causal analysis tools. Mechanisms can also be organized into catalogues and have checklists. Mechanisms provide software internal links between software construction, post-construction, and deconstruction pattern paradigms.
The resulting iterative and incremental A.P.M. methodology (Artifacts. Patterns. Mechanisms.) is illustrated in the following diagram:
The forthcoming volumes of Memory Dump Analysis Anthology (from volume 9) will now include Software Problem Mechanisms and Pattern-Oriented Root Cause Analysis Case Studies chapters in addition to usual pattern chapters.