Goroutine spawned without context or stop channel

Playbook ID: goroutine-leak Category: runtime Severity: high Tags: source, go, goroutine, leak, context, concurrency

What this failure means

A goroutine is spawned with an infinite loop and no context cancellation, stop channel, or WaitGroup — it will leak when the calling function returns.

Common log signals

(This playbook uses source-code pattern matching rather than log signals.)

Diagnosis

A goroutine is started with go func() and runs an infinite or long-running loop without any mechanism to stop it. When the parent context or server shuts down, this goroutine keeps running, leaking memory and CPU over time.

Common patterns:

• A background poller that loops with time.Sleep and no shutdown signal
• A cache-refresh goroutine that runs forever without a done channel
• A background worker spawned in init() or main() without lifecycle control

Fix steps

1. Accept a context.Context parameter and check ctx.Done() in the loop:

   func StartWorker(ctx context.Context) {
       go func() {
           for {
               select {
               case <-ctx.Done():
                   return
               default:
                   doWork()
                   time.Sleep(time.Second)
               }
           }
       }()
   }
   

2. Alternatively, use a stop channel: stop <- struct{}{} from the caller and case <-stop: return in the goroutine select.

3. Track goroutines with a sync.WaitGroup so callers can wait for clean shutdown.

4. For periodic background work, prefer time.NewTicker with a select over time.Sleep in a loop — the ticker can be stopped.

Validation

• Run faultline inspect . from the repository root and confirm this source finding is absent or intentionally mitigated.
• Run go test -race ./... to catch races introduced during cleanup.
• Confirm that the background goroutine exits cleanly when the context is cancelled.

Likely files to inspect

• worker.go
• background.go
• scheduler.go
• poller.go
• server.go

Run Faultline

faultline analyze build.log
faultline explain goroutine-leak
faultline workflow build.log --json --mode agent

Search phrases this page answers

• Goroutine spawned without context or stop channel
• Runtime: goroutine spawned without context or stop channel
• faultline explain goroutine-leak
• Go goroutine spawned without context or stop channel

---

Generated from playbooks/bundled/source/goroutine-leak.yaml. Do not edit directly — run make docs-generate.