go data_error ai_generated true

error: unexpected zero value received (channel closed, ok=false ignored)

ID: go/receive-from-closed-channel-zero-value

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-04-08First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.18 active — — —
1.21 active — — —

Root Cause

Reading from a closed channel returns the zero value immediately forever. Code that ignores the 'ok' bool treats zero values as real data, causing silent corruption.

generic

中文

从已关闭的 channel 读取会永远立即返回零值。忽略 'ok' 布尔值的代码把零值当作真实数据，造成静默的数据损坏。

Workarounds

  1. 95% success 
    Use the comma-ok idiom: 'v, ok := <-ch; if !ok { return }' and break the loop on close
  2. 93% success 
    Use 'for v := range ch { ... }' which terminates automatically when the channel closes

Dead Ends

Common approaches that don't work:

  1. 80% fail

    Closed channel always returns immediately; sleep just delays the wrong value

  2. 85% fail

    len is a snapshot and racy; does not distinguish closed from empty