go runtime_error ai_generated true

panic: sync: negative WaitGroup counter

ID: go/waitgroup-add-positive-delta

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-02-14First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.18 active — — —
1.20 active — — —
1.22 active — — —

Root Cause

wg.Done() is called more times than wg.Add(). Usually a missing Add before launching a goroutine, a double defer wg.Done(), or Done called in a loop path that runs more than the added count.

generic

中文

wg.Done() 的调用次数多于 wg.Add()。通常是因为启动 goroutine 前漏了 Add、重复 defer wg.Done()，或 Done 在循环路径中执行次数超过 Add 的数量。

Workarounds

  1. 96% success 
    wg.Add(1)
go func() {
    defer wg.Done()
    work()
}()
  2. 90% success 
    func launch(wg *sync.WaitGroup, f func()) {
    wg.Add(1)
    go func() { defer wg.Done(); f() }()
}

Dead Ends

Common approaches that don't work:

  1. 70% fail

    Masks the real double-Done bug and can cause Wait to hang forever if the count never reaches zero.

  2. 90% fail

    Wait then blocks forever because the counter never decrements.