go runtime_error ai_generated true

panic: send on closed channel

ID: go/panic-runtime-error-send-on-closed-channel

Also available as: JSON · Markdown · 中文
85%Fix Rate
85%Confidence
1Evidence
2023-06-15First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
go1.21 active — — —
go1.22 active — — —
go1.23 active — — —

Root Cause

Attempting to send a value on a channel that has already been closed, which violates the channel contract.

generic

中文

尝试向已关闭的通道发送值，违反了通道的使用约定。

Official Documentation

https://go.dev/ref/spec#Close

Workarounds

  1. 90% success Ensure the channel is closed only by the sender after all sends are complete. Use a sync.WaitGroup to coordinate goroutines, and close the channel in a dedicated goroutine after Wait. 
    Ensure the channel is closed only by the sender after all sends are complete. Use a sync.WaitGroup to coordinate goroutines, and close the channel in a dedicated goroutine after Wait.
  2. 85% success Use a select statement with a default case to check if the channel is closed before sending, or use a separate closed channel for signaling. 
    Use a select statement with a default case to check if the channel is closed before sending, or use a separate closed channel for signaling.

中文步骤

  1. Ensure the channel is closed only by the sender after all sends are complete. Use a sync.WaitGroup to coordinate goroutines, and close the channel in a dedicated goroutine after Wait.
  2. Use a select statement with a default case to check if the channel is closed before sending, or use a separate closed channel for signaling.

Dead Ends

Common approaches that don't work:

  1. Adding a time.Sleep before closing the channel to avoid race conditions. 85% fail

    Race conditions are timing-dependent; adding sleep does not guarantee ordering and may hide the bug rather than fix it.

  2. Using recover() in a deferred function to catch the panic. 70% fail

    Recovering from a panic does not fix the root cause; the channel was already misused and data may be lost.

  3. Closing the channel after all sends are done by adding a sync.WaitGroup but not calling WaitGroup.Wait() correctly. 60% fail

    Incorrect WaitGroup usage leads to same race: close happens before all sends complete.