• In software, an architectural cycle is when a component's calls to other components loop back to itself.

• Cyclicality really hurts software quality!

  • Components involved in cycles have more bugs than non-cycle components.

  • The larger the cycle, the more bugs associated with each of its component.

  • The implications of cyclicality are at least as important as those of modularity.

• The more central a component in a cycle, the more bugs it tends to have.

  • Centrality is the number of paths that link a component in a cycle back to itself.

  • Central components have to incorporate more potential changes propagated via their high connectivity.

• Failing to encapsulate cycles within a module hurts quality even more.

  • Multi-module cycles are common.

  • The average number of bugs exhibited by an in-cycle component increases with the number of modules involved in the cycle.

  • Developers seem to neglect the negative consequences of dealing with cyclical dependencies across modules, or are not aware of such cycles.

Key Publications:  P26, P24, C17, O28