Action Deduplication: Faster and Cheaper Remote Builds Without Lifting a Finger
summary
Remote Bazel RBE backends implement action deduplication (aka merging/coalescing) so identical actions already executing are not re-run; BuildBuddy, Buildbarn and Inflow-style services provide it. Canva measures a 66% unnecessary rerun rate for 7–10 minute webpack actions, yielding only ~$10k/year saved, but UI tests see ~500k deduplications/day with ~100s average runs and save hundreds of thousands in compute. Expect clustered flaky-test failures and consider alerting or detection changes.
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chapters (9)
- 0:00Action deduplication intro
- 1:03Remote execution without dedup
- 2:26How dedup prevents redundant work
- 3:30Why dedup matters in CI
- 4:56Dedup in main branch builds
- 6:19Building only changed targets isn't always better
- 7:42Real-world cost savings
- 9:07When to enable dedup
- 9:27Flaky tests and failure clustering
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