Hi All, We want to create upstream change to Maven to support true incremental build for big-sized projects. To raise a pull request we have to pass long chain of Deutsche Bank's internal procedures. So, before starting the process we would like to get your feedback regarding this feature.
Motivation: Our project is hosted in mono-repo and contains ~600 modules. All modules has the same SNAPSHOT version. There are lot of test automation around this, everything is tested before merge into release branch. Current setup helps us to simplify build/release/dependency management for 10+ teams those contribute into codebase. We can release everything in 1-click. The major drawback of such approach is build time: full local build took 45-60 min (-T8), CI build ~25min(-T16). To speed-up our build we needed 2 features: incremental build and shared cache. Initially we started to think about migration to Gradle or Bazel. As migration costs for the mentioned tools were too high, we decided to add similar functionality into Maven. Current results we get: 1-2 mins for local build(-T8) if build was cached by CI, CI build ~5 mins (-T16). Feature description: The idea is to calculate checksum for inputs and save outputs in cache. [image2019-8-27_20-0-14.png] Each node checksum calculated with: * Effective POM hash * Sources hash * Dependencies hash (dependencies within multi-module project) Project sources inputs are searched inside project + all paths from plugins configuration: [image2019-8-30_10-28-56.png] How does it work in practice: 1. CI: runs builds and stores outputs in shared cache 2. CI: reuse outputs for same inputs, so time is decreasing 3. Locally: when I checkout branch and run 'install' for whole project, I get all actual snapshots from remote cache for this branch 4. Locally: if I change multiple modules in tree, only changed subtree is rebuilt Impact on current Maven codebase is very localized (MojoExecutor, where we injected cache controller). Caching can be activated/deactivated by property, so current maven flow will work as is. And the big plus is that you don't need to re-work your current project. Caching should work out of box, just need to add config in .mvn folder. Please let us know what do you think. We are ready to invest in this feature and address any further feedback. Kind regards, Max --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. Please refer to https://www.db.com/disclosures for additional EU corporate and regulatory disclosures and to http://www.db.com/unitedkingdom/content/privacy.htm for information about privacy.
