go runtime_error ai_generated true

panic: sync: negative WaitGroup counter

ID: go/negative-waitgroup-counter

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-03-11First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.16+ active — — —

Root Cause

wg.Done() called more times than wg.Add(), commonly when Done is deferred inside a goroutine that also returns early or when Add is called inside the goroutine itself.

generic

中文

wg.Done() 的调用次数多于 wg.Add()，通常发生在 goroutine 内 defer Done 且提前返回，或 Add 在 goroutine 内部调用时。

Workarounds

  1. 95% success 
    wg.Add(1)
go func() {
    defer wg.Done()
    doWork()
}()
wg.Wait()
  2. 92% success 
    g := new(errgroup.Group)
for _, item := range items {
    item := item
    g.Go(func() error { return process(item) })
}
if err := g.Wait(); err != nil { return err }

Dead Ends

Common approaches that don't work:

  1. 85% fail

    recover cannot catch this panic reliably across goroutine boundaries and masks the real imbalance, causing the Wait() to return prematurely.

  2. 90% fail

    The counter imbalance is structural; sleeping only changes timing and the panic still fires when Done exceeds Add.