Merge time

What is merge time?

Merge time is a software engineering metric that measures the average duration from when code is approved for merging until it is successfully merged into the main branch of a project. This metric helps teams understand the efficiency and speed of their code integration process. To calculate merge time, you would typically gather data on the timestamp when code is approved for merging and the timestamp when the merge is completed. The difference between these times, averaged over a certain period or across various merges, gives you the merge time.

Why is merge time important?

Efficiency of the development process. Merge time is critical because it directly influences the overall efficiency of the software development lifecycle. Shorter merge times mean that updates and improvements can be integrated into the main branch more quickly, which accelerates development cycles and enables faster iteration.

Software quality and stability. Keeping merge times minimal helps in maintaining the quality and stability of the software. Longer merge times can lead to a pile-up of branches, which increases the complexity of integration and the likelihood of conflicts or bugs. Efficient merging ensures that code integrations are manageable and errors are caught and resolved early.

Team productivity and collaboration. Merge time also impacts team dynamics. A shorter merge time often reflects better collaboration and coordination among team members. It ensures that team members are not waiting too long for their contributions to be integrated, which can boost morale and productivity.

What are the limitations of merge time?

Does not measure code quality. Although merge time can indicate process efficiency, it does not directly assess the quality of the code being merged. A quick merge time might lead to unreviewed or insufficiently tested code being added to the main branch, potentially leading to quality issues down the line.

Varies with team size and structure. Merge time can vary significantly depending on the size of the team and its structure. Larger teams or teams with more hierarchical structures might experience longer merge times due to more complex review processes or communication delays, which does not necessarily indicate inefficiency.

Influenced by external factors. Several external factors can affect merge time, such as tool performance, system outages, or operational challenges. These factors can distort the metric, making it a less reliable indicator of team performance or process efficiency.

Metrics related to merge time

Cycle time. Cycle time is closely related to merge time as it measures the total time from when work starts on a piece of code until it is completed, which includes the merge time. Understanding both metrics together provides a comprehensive view of the efficiency and speed of the entire development process, from coding through to integration.

Review time. Review time measures the duration from when a pull request is made until it is approved. Since review time directly precedes merge time, any delays or efficiencies in the review process will impact the overall merge time. Tracking both metrics can help teams identify bottlenecks in the pre-merge phase.

Build time. Build time measures how long it takes to execute a build of the software. Although it is a post-merge activity, efficient merging can influence build time by ensuring that the code integrated into the main branch is stable and less likely to cause build failures. Monitoring build time in conjunction with merge time can help teams gauge the impact of integration practices on subsequent stages of development.