Ignominy: tool for analysing software dependencies and for reducing complexity in large software systems

LHC experiments such as CMS have large-scale software projects that are challenging to manage. We present Ignominy, a tool developed in CMS to help us deal better with complex software systems. Ignominy analysis the source code as well binary products such as libraries and programs to deliver a comprehensive view of the package dependencies, including all the external products used by the project. We describe the analysis and the various charts, diagrams and metrics collected by the tool, including results from several large-scale HEP software projects. We also discuss the progress made in CMS to improve the software structure and the experience we have gained in physical packaging and distribution of our code.