go runtime_error ai_generated true

panic: sync: Once is reused

ID: go/once-reuse-panic

Also available as: JSON · Markdown · 中文
80%Fix Rate
80%Confidence
0Evidence
2024-01-18First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.19 active — — —

Root Cause

Attempting to reuse a sync.Once after it has been used, which is not allowed.

generic

中文

在 sync.Once 已被使用后再次尝试使用它，这是不允许的。

Workarounds

  1. 90% success 
    Use a flag with atomic operations to implement single execution: 

var done int32
go func() {
    if atomic.CompareAndSwapInt32(&done, 0, 1) {
        // do once
    }
}()
  2. 85% success 
    Ensure Once is used only once per lifecycle, and create a new instance if needed.

Dead Ends

Common approaches that don't work:

  1. 90% fail

    Copying a sync.Once is unsafe and can cause races; it's not designed to be copied.

  2. 40% fail

    If the Once is embedded in a struct that's reused, it may still be copied.