go runtime_error ai_generated true

panic: sync: negative WaitGroup counter

ID: go/goroutine-negative-waitgroup-counter

Also available as: JSON · Markdown · 中文
80%Fix Rate
87%Confidence
0Evidence
2024-04-12First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.21 active — — —
1.22 active — — —

Root Cause

Calling Done() on a WaitGroup more times than Add() was called, often due to mismatched goroutine lifecycle management.

generic

中文

对WaitGroup调用Done()的次数超过Add()调用的次数，通常是由于协程生命周期管理不匹配。

Workarounds

  1. 98% success Ensure Add() is called exactly once per goroutine before starting it 
    var wg sync.WaitGroup
for i := 0; i < n; i++ {
    wg.Add(1)
    go func() {
        defer wg.Done()
        // work
    }()
}
wg.Wait()
  2. 80% success Use atomic counter with careful increment/decrement 
    var counter int64
atomic.AddInt64(&counter, 1)
go func() {
    // work
    atomic.AddInt64(&counter, -1)
}()

Dead Ends

Common approaches that don't work:

  1. Adding recover() to catch the panic 90% fail

    Recover does not fix the underlying counter mismatch; it only hides the symptom.

  2. Increasing Add() calls arbitrarily 85% fail

    This can lead to other goroutines waiting indefinitely if Done() is not called enough times.