go runtime_error ai_generated true

panic: send on closed channel

ID: go/goroutine-send-on-closed-channel

Also available as: JSON · Markdown · 中文
80%Fix Rate
85%Confidence
0Evidence
2024-01-15First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.21 active — — —
1.22 active — — —

Root Cause

Sending data to a channel that has already been closed, typically due to multiple goroutines sending without proper synchronization of channel closure.

generic

中文

向已经关闭的通道发送数据，通常是由于多个协程发送数据时没有正确同步通道的关闭操作。

Workarounds

  1. 95% success Use a sync.Mutex to coordinate sends and close 
    var mu sync.Mutex
ch := make(chan int)
closeCh := func() {
    mu.Lock()
    defer mu.Unlock()
    close(ch)
}
send := func(v int) {
    mu.Lock()
    defer mu.Unlock()
    ch <- v
}
  2. 90% success Use a select with default to avoid send on closed channel 
    select {
case ch <- v:
default:
    // handle failure or retry
}

Dead Ends

Common approaches that don't work:

  1. Checking channel state with a flag before sending 75% fail

    Race condition: the channel could be closed between the check and the send, leading to a panic.

  2. Using recover() to catch the panic and continue 85% fail

    Recovering from a panic does not prevent data loss or corruption, and the program state may be inconsistent.