On combining commit grouping and build skip prediction to reduce redundant continuous integration activity

Context

Continuous Integration (CI) is a resource intensive, widely used industry practice. The two most commonly used heuristics to reduce the number of builds are either by grouping multiple builds together or by skipping builds predicted to be safe. Yet, both techniques have their disadvantages in terms of missing build failures and respectively higher build turn-around time (delays).

Objective

We aim to bring together these two lines of research, empirically comparing their advantages and disadvantages over time, and proposing and evaluating two ways in which these build avoidance heuristics can be combined more effectively, i.e., the ML-CI model based on machine learning and the Timeout Rule.

Method

We empirically study the trade-off between reduction in the number of builds required and the speed of recognition of failing builds on a dataset of 79,482 builds from 20 open-source projects.

Results

We find that both of our hybrid heuristics can provide a significant improvement in terms of less missed build failures and lower delays than the baseline heuristics. They substantially reduce the turn-around-time of commits by 96% in comparison to skipping heuristics, the Timeout Rule also enables a median of 26.10% less builds to be scheduled than grouping heuristics.

Conclusions

Our hybrid approaches offer build engineers a better flexibility in terms of scheduling builds during CI without compromising the quality of the resulting software.