ci: the race detector runs in four parts - #135
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The whole of internal/guard under -race took 32 to 42 minutes, and six of the twelve runs on 2026-09-23 and 2026-09-24 were killed at the 45 minute ceiling with no data race in their logs. It is the only package with tests (1714 s of the 32 minutes in the last green run), and none of its tests calls t.Parallel, so four processes each take about a quarter. Each part lists the tests with the flags of the run - -race, because raceflag_test.go builds only without it, and Test, Fuzz and Example, because go test runs all three - sorts them and takes every fourth from strategy.job-index. No list is kept by hand, so a new guard lands in a part by itself. go test with a -run pattern that matches nothing exits 0, so a part fails rather than passing on nothing when the matrix and the index disagree, when it is given no test, or when it ran fewer top-level tests than it was given. Part 0 also runs every other package under the detector. Ceilings per part: 30 minutes for the job, 25 for Go. fail-fast is off, so one red part does not leave the others' tests unrun. ci.yml joins the watched list, so a change to this job runs it rather than waiting for the weekly sweep. Checked before pushing: the step's script, taken out of the workflow by a YAML parser and run on this machine with -race removed, is red for each of the four failure cases - including one test skipped, where go test itself said ok - and green for part 0, 238 of 953 tests. actionlint with shellcheck reports nothing. Co-Authored-By: Claude Opus 5.5 <[email protected]>
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📝 WalkthroughWalkthroughThe CI workflow now watches its own file and ChangesRace Test Workflow
Priority: ⬇️ Low Estimated code review effort: 2 (Simple) | ~12 minutes Change: Other Merge Risk: ⚪ Minimal · up to The race-test workflow is mergeable after normal checks; no concrete coverage or execution failure remains identified. 🚥 Pre-merge checks | ✅ 11 | ❌ 3❌ Failed checks (3 warnings)
✅ Passed checks (11 passed)
Full details: No Obvious Performance ProblemsExplanation The new race workflow starts one external Full details: Clear User-Facing TextExplanation The PR adds CI error messages at Resolution Replace the messages with actionable text. For example: Full details: Scope, Duplication And DocsExplanation The PR is otherwise in scope and the title/description cover the race-detector redesign. However, the authoritative diff changes the CI configuration and build/test steps only in Resolution Update the project documentation, preferably ✨ Finishing Touches🧪 Generate unit tests (beta)
✨ Simplify code
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Reverted by the next commit, before merging. Expected: the part holding TestADataRaceOnPurposeForTheRaceJob (part 0 by the sorted list) red with DATA RACE, parts 1 to 3 green. Co-Authored-By: Claude Opus 5.5 <[email protected]>
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In @.github/workflows/ci.yml:
- Line 700: Add `.github/build-tags` to the `watched` file list so changes to
the race job’s build tags trigger the detector instead of being skipped.
- Around line 857-861: Add an aggregate timeout around the other-packages `go
test` invocation in the `PART` equals 0 block, leaving enough time for setup and
the preceding guard tests before the 30-minute job limit; retain the per-package
Go test timeout as a separate limit.
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- GitHub Check: race detector (part 2 of 4)
- GitHub Check: race detector (part 0 of 4)
- GitHub Check: race detector (part 3 of 4)
- GitHub Check: race detector (part 1 of 4)
- GitHub Check: test on windows-latest
- GitHub Check: test on macos-latest
- GitHub Check: bill of materials
- GitHub Check: test on ubuntu-latest
- GitHub Check: import table of the window binary
- GitHub Check: reference tools actually installed
- GitHub Check: coverage gate
- GitHub Check: known vulnerabilities
- GitHub Check: staticcheck
- GitHub Check: linters
- GitHub Check: semgrep
- GitHub Check: Analyze (go)
- GitHub Check: Analyze (actions)
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804-856: LGTM!
734-734: 🎯 Functional CorrectnessThe current evidence does not establish that branch protection requires the old
race detectorcheck name. The ruleset response lists required checks but does not includerace detector. The branch-protection endpoint returned403 Resource not accessible by integration, so branch-protection requirements remain unknown. The possible merge-blocking failure cannot be decided.
…d build-tags runs the job Go's -timeout holds one test binary, so the other packages running after the guards in the same step added up under nothing but the job's ceiling. They now run in a step of their own in part 0, with timeout-minutes 5 and -timeout 4m, and after red guards as well. The job's ceiling is the sum of the limits inside it with room over: about four minutes to set up and compile (3m03s measured), 20 for the guards (1.8 times the slowest part, 677 s), 5 for the other packages - 35 minutes. .github/build-tags is read by every command of the job and decides the files it compiles, so a change to it now runs the job, like go.mod. Both from the review of the pull request. Co-Authored-By: Claude Opus 5.5 <[email protected]>
It showed what it was there for: part 0 red with WARNING: DATA RACE on TestADataRaceOnPurposeForTheRaceJob and nothing else failing, all 238 of its tests run, its other-packages step run after the red guards, part 3 green. Co-Authored-By: Claude Opus 5.5 <[email protected]>
…ves no other The first version gave each part every fourth name of a sorted list. A temporary guard added on this pull request moved every name after it by one, and part 0 went from 677 s of guards to 145 s - the part holding the slowest guards changed from one commit to the next. A test's part is now cksum of its name modulo the number of parts, so adding or removing a test moves nothing else, and a slow part is slow because of what is in it. Predicted from the first run's times under -race, before this run: 264, 225, 222 and 242 tests, 296, 449, 658 and 220 s of guards. The two slowest (329 and 222 s) share part 2. Even only on average, and said so. Checked locally with the step taken out of the workflow: the four parts together hold each of the 953 tests exactly once, the three failure cases are red and a real part is green. Co-Authored-By: Claude Opus 5.5 <[email protected]>
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…ver ran The four ways a part fails before or after its tests said what happened and not what to do about it - the review's pre-merge check named it. Each now says what to change. The one that counts runs lists the names given to the part and never run, instead of two numbers. The review's suggested text ended every message with rerunning. All four failures are deterministic, so a rerun repeats them, and that part was not taken. Co-Authored-By: Claude Opus 5.5 <[email protected]>
…iven The check counted top-level starts against the tests given. A stray line at column 0 that looks like a start, together with one test that never ran, would have added up and passed. It now compares the two sets of names, so a start can only stand for the test it names. None of the guards writes to stdout directly and the package has no Example today, so this was not reachable - it is the same check made to rest on the names. Checked locally with the step taken out of the workflow: one test skipped is named and red, a real part is green. Co-Authored-By: Claude Opus 5.5 <[email protected]>
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The race detector job runs
internal/guardin four parts instead of one.Why
The whole package under
-racetook 32-42 minutes. Six of the twelve runs on 2026-09-23 and 2026-09-24 were killed at the 45 minute ceiling, and none of their logs has aDATA RACE. Both ceilings had already been raised once, on 2026-08-31.internal/guardis the only package with tests (1714 s of the last green run's 32 minutes), and none of its tests callst.Parallel, so four processes share the time.How a part knows its tests
-race, becauseraceflag_test.gobuilds only without it. It keepsTest,FuzzandExample, becausego testruns all three.cksumof the name modulo the number of parts is itsstrategy.job-index.The first version took every fourth name of a sorted list. A temporary guard added on this PR moved every name after it, and part 0 went from 677 s of guards to 145 s. The parts are even only on average: the two slowest guards (329 and 222 s) share one part.
go testexits 0 when a-runpattern matches nothing. So a part fails instead of passing on nothing in three cases:job-indexdisagreeOther changes
fail-fast: false, so one red part does not cancel the others..github/workflows/ci.ymland.github/build-tagsjoin thewatchedlist, so a change to the job or to the tags runs it.Seen on this PR
818d0d2, with 677, 635, 164 and 154 s of guards. The whole job took about 15 minutes, down from 32.87df5c1turned the part holding it red withWARNING: DATA RACE. That test was the only failure, all 238 tests of the part ran, and the other-packages step still ran. The other parts stayed green.1677725reverts it, and all four parts are green again there.-raceremoved. It was red for each failure case, including one test skipped with-skipwhilego testitself saidok. With the checksum split, the four parts together hold each of the 953 tests exactly once.This changes
.github/workflows/ci.yml, so it has to be merged from the browser.🤖 Generated with Claude Code
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