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test: set test flags from within an init to limit maximum test parallelism#19575

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Merged

Emyrk merged 6 commits intomainfromstevenmasley/limit_parallel

Sep 17, 2025

Merged

test: set test flags from within an init to limit maximum test parallelism#19575

Emyrk merged 6 commits intomainfromstevenmasley/limit_parallel

Sep 17, 2025

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Emyrk commentedAug 27, 2025•
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What this does

This limits the maximum test parallelism to8 by default, matching theMakefile. This will improve the success rate of runninggo test natively.

On systems with less than 8 cores (GOMAXPROCS < 8), this code is a no-op. The smaller number will still be the default. On those systems,go test may still fail due to resource contention between tests.

Manually setting-parallel=<n> still works exactly as expected

Example test and output with the max parallelism set to 1

package paralleltest_testimport ("strconv""testing""time"_"github.com/coder/coder/v2/coderd/coderdtest")varcount=0funcTestParallelism(t*testing.T) {t.Parallel()fori:=0;i<5;i++ {t.Run(strconv.Itoa(i),func(t*testing.T) {t.Parallel()count++time.Sleep(time.Second)})}}

go test ./... -v -count=1=== RUN   TestParallelism=== PAUSE TestParallelism=== CONT  TestParallelism=== RUN   TestParallelism/0=== PAUSE TestParallelism/0=== RUN   TestParallelism/1=== PAUSE TestParallelism/1=== RUN   TestParallelism/2=== PAUSE TestParallelism/2=== RUN   TestParallelism/3=== PAUSE TestParallelism/3=== RUN   TestParallelism/4=== PAUSE TestParallelism/4=== CONT  TestParallelism/0=== CONT  TestParallelism/2=== CONT  TestParallelism/1=== CONT  TestParallelism/4=== CONT  TestParallelism/3--- PASS: TestParallelism (0.00s)    --- PASS: TestParallelism/0 (1.00s)    --- PASS: TestParallelism/2 (1.00s)    --- PASS: TestParallelism/1 (1.00s)    --- PASS: TestParallelism/4 (1.00s)    --- PASS: TestParallelism/3 (1.00s)PASSok      github.com/coder/coder/v2/coderd/coderdtest/paralleltest        5.023s

When you manually set the parallel:

go test ./... -v -count=1 -parallel=5=== RUN   TestParallelism=== PAUSE TestParallelism=== CONT  TestParallelism=== RUN   TestParallelism/0=== PAUSE TestParallelism/0=== RUN   TestParallelism/1=== PAUSE TestParallelism/1=== RUN   TestParallelism/2=== PAUSE TestParallelism/2=== RUN   TestParallelism/3=== PAUSE TestParallelism/3=== RUN   TestParallelism/4=== PAUSE TestParallelism/4=== CONT  TestParallelism/0=== CONT  TestParallelism/4=== CONT  TestParallelism/3=== CONT  TestParallelism/1=== CONT  TestParallelism/2--- PASS: TestParallelism (0.00s)    --- PASS: TestParallelism/2 (1.00s)    --- PASS: TestParallelism/4 (1.00s)    --- PASS: TestParallelism/0 (1.00s)    --- PASS: TestParallelism/1 (1.00s)    --- PASS: TestParallelism/3 (1.00s)PASSok      github.com/coder/coder/v2/coderd/coderdtest/paralleltest        1.020s

test: experimenting setting test flags from within an init()

8117381

github-actionsbot assignedEmyrk

Aug 27, 2025

Emyrk added2 commits

August 27, 2025 08:55

change how the flag is set

a9fc3c9

whoops

d53c1b5

github-actionsbot added the staleThis issue is like stale bread. label

Sep 4, 2025

github-actionsbot closed this

Sep 7, 2025

Emyrk reopened this

Sep 12, 2025

github-actionsbot removed the staleThis issue is like stale bread. label

Sep 13, 2025

chore: change parallism to 8, add helpful panic message

f004c68

Emyrk marked this pull request as ready for review

September 16, 2025 16:38

Emyrk changed the title~~test: experimenting setting test flags from within an init()~~test: set test flags from within an init to limit maximum test parallelism

Sep 16, 2025

remove test

f3b28ea

Emyrk requested review fromdannykopping,johnstcn andspikecurtis

September 16, 2025 18:37