Merge Request Average Lifetime
- Natallia_Mendzel@epam.com
- Denis Olevanov (Unlicensed)
- Ivan_Kaschenko
- Aleksandr Bogush
Purpose
Merge Request Average Lifetime shows an average speed of new changes being incorporated to a master code due to delays on code reviews. The less the better - means less overhead for a development process/team to handle merges.
Terminology alignment
PERF supports multiple variations of GIT, which have a different naming for the piece of code change willing to be merged to some target branch through the process of code review. Just to remove the confusion, this metric represents a holistic approach for:
Type of a GIT | Term |
|---|---|
GitLab | Merge request |
GitHub | Pull request |
Bitbucket | Pull request |
Azure DevOps Repos | Pull request |
How metric helps
It allows monitoring aged merge requests, on average, by weeks. Stale merge requests, i.e. which took long time for reviewed and acceptance, usually have a higher cost for a team in comparison with short-living merges. Why? Stale merges require more attention at review and acceptance of a code change - because of higher probability of conflicts with a target branch.
Possible reasons why stale merge requests might appear:
risky merge e.g. due to a not-easy-to-review change or a big change
not enough capacity (or level of engineering culture) in the team to review the code on timely basis
General recommendation is to have the lifetime of merge requests as small as possible.
How metric works
Chart overview
Chart shows Merge Request Average Lifetime in hours (axis Y) by week (axis X). Chart can consist of several series according to a number of branches selected in Project Settings.
Only accepted merge requests take part in this metric. Merge requests pending review are not counted here, no matter how long they stay open.
By click on a series a hint with additional details appears:
Branch - branch name; got from Project settings
Week - time period the series is built for
Merge Requests accepted - number of accepted requests
Average Merge Requests lifetime - lifetime, in hours, for the merge requests accepted during this week
Longest Merge Requests - top 5 merge requests with the longest lifetime at that week
Next to the chart name there is a link to navigate to the GIT repository ('arrow' icon) for further details.
Calculation formula
Tmr = Tmerge - Tcreation
Merge Request Average Lifetime = ∑Tmr/Nmr
where
Tmr - time spent for a merge request
Nmr - number of all merge requests existing
Notices:
Cancelled requests are NOT included in calculation.
Merge requests are distributed between weeks in the chart by their merge date.
RAG thresholds: Red > 240 hours, Green < 120 hours (can be adjusted per project).
Data Source
Data for the metric can be collected from GIT.