go runtime_error ai_generated true

panic: sync: negative WaitGroup counter

ID: go/deadlock-waitgroup-misuse

Also available as: JSON · Markdown · 中文
80%Fix Rate
86%Confidence
0Evidence
2024-02-28First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.18 active — — —

Root Cause

Calling Done() more times than Add() causes the counter to go negative, panicking.

generic

中文

调用 Done() 的次数多于 Add()，导致计数器变为负数，引发恐慌。

Workarounds

  1. 95% success 
    var wg sync.WaitGroup
wg.Add(1)
go func() {
    defer wg.Done()
    // work
}()
wg.Wait()
  2. 90% success 
    // Ensure Add is called before starting goroutines
wg.Add(2)
go func() { defer wg.Done(); /* work */ }()
go func() { defer wg.Done(); /* work */ }()
wg.Wait()

Dead Ends

Common approaches that don't work:

  1. 70% fail

    Recovery doesn't fix the logic error; program state is inconsistent.

  2. 100% fail

    Panic crashes the program unless recovered.

  3. 80% fail

    Doesn't prevent negative if Done is called too many times.