Wait Group Misuse (ARCH5037)

Key go.async.waitgroup-misuse · Severity warning · Category async

Misusing sync.WaitGroup - calling wg.Add inside the goroutine instead of before launch, or omitting defer wg.Done() - causes races against Wait or hangs forever when a goroutine panics.

Incorrect

func RunAll(tasks []func()) {
  var wg sync.WaitGroup
  for _, t := range tasks {
    go func(fn func()) {
      wg.Add(1) // after launch; may miss Wait
      fn()
    }(t)
  }
  wg.Wait()
}

Correct

func RunAll(tasks []func()) {
  var wg sync.WaitGroup
  for _, t := range tasks {
    wg.Add(1)
    go func(fn func()) {
      defer wg.Done()
      fn()
    }(t)
  }
  wg.Wait()
}

Fix

Call wg.Add(1) before launching the goroutine and use defer wg.Done() at its top.