Engineering Effectiveness Newsletter (March 2022 Edition)

Welcome to the March edition of the Engineering Effectiveness Newsletter! The Engineering Effectiveness org makes it easy to develop, test and release Mozilla software at scale. See below for some highlights, then read on for more detailed info!


  • MozillaBuild 4.0 is released! Featuring better hg integration, a modernized raft of Linux tools, and a migration from Python 2 to Python 3.
  • All non-shippable builds have been migrated from AWS to GCP! This results in a nice little cost savings, but more importantly gets the ball rolling on the overall migration to GCP in our CI.
  • Two weekend releases were successfully shipped! First a chemspill release and next to remove Yandex, all in addition to the regularly scheduled releases.


  • anastasiostam

Detailed Project Updates

Bugzilla and Bugbug

Build System and Mach Environment

CI and Treeherder

Crash Management

Lint, Static Analysis and Code Coverage

  • Marco fixed grcov’s CI, which had been broken for a while after the switch from Travis/Appveyor to GitHub Actions
  • Sylvestre fixed and validated the trojan source linter

Phabricator , moz-phab, and Lando

  • Mitch drastically lowered the number of emails submitted by Phabricator, emails will no longer be sent due to changes in parent revisions
  • Sheehan removed a dependency on .arcconfig that caused revisions to move between repositories erroneously on merge
  • Sheehan added a warning to moz-phab when hg is used without evolve

Release Engineering and Management

Version Control

  • Sheehan added clonebundles to new GCP regions, improving clone times in CI as we migrate to GCP
  • Sheehan fixed a bug in pushlog that sometimes caused changesets to land without pushlog information


Thanks for reading and see you next month!