Go race detector found a data race

Playbook ID: go-data-race Category: test Severity: high Tags: go, race, concurrency, data-race, test

What this failure means

The Go race detector identified a data race: two goroutines accessed the same memory location concurrently, with at least one performing a write, without any synchronization between them.

Common log signals

WARNING: DATA RACE
DATA RACE
Previous read at
Previous write at
Read at 0x
Write at 0x
Goroutine.*running
PASS (race)

Diagnosis

The Go race detector identified a data race: two goroutines accessed the same memory location concurrently, with at least one performing a write, without any synchronization between them.

Fix steps

1. Read the full race report — it shows both goroutine stacks and the file/line for each conflicting access.
2. Protect the shared variable with sync.Mutex or sync.RWMutex, or use an atomic operation (sync/atomic) for simple counters.
3. Replace concurrent map access with sync.Map or add a sync.RWMutex around reads and writes.
4. For loop-variable captures: copy the variable into a local before launching the goroutine: v := v.
5. Run locally to reproduce: go test -race ./... or go test -race -count=5 ./... for intermittent races.

Validation

• Re-run the local reproduction command after the fix.
• go test -race ./...
• go test -race -count=10 ./path/to/package

Likely files to inspect

• **/*.go

Run Faultline

faultline analyze build.log
faultline explain go-data-race
faultline workflow build.log --json --mode agent

Search phrases this page answers

• Go race detector found a data race
• Test: go race detector found a data race
• WARNING: DATA RACE
• faultline explain go-data-race
• Go go race detector found a data race

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Generated from playbooks/bundled/log/test/go-data-race.yaml. Do not edit directly — run make docs-generate.