go runtime_error ai_generated true

fatal error: concurrent slice writes

ID: go/goroutine-slice-append-race

Also available as: JSON · Markdown · 中文
80%Fix Rate
86%Confidence
0Evidence
2024-11-22First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.20 active — — —
1.21 active — — —

Root Cause

Multiple goroutines append to the same slice without synchronization, causing a data race.

generic

中文

多个协程在没有同步的情况下追加到同一个切片，导致数据竞争。

Workarounds

  1. 95% success Use a mutex to protect slice appends. 
    var mu sync.Mutex
var slice []int

func appendValue(v int) {
    mu.Lock()
    slice = append(slice, v)
    mu.Unlock()
}
  2. 90% success Use a channel to aggregate results from goroutines. 
    ch := make(chan int, 100)
for i := 0; i < n; i++ {
    go func() {
        ch <- compute()
    }()
}
var results []int
for i := 0; i < n; i++ {
    results = append(results, <-ch)
}

Dead Ends

Common approaches that don't work:

  1. Using a channel to serialize appends but not draining the channel properly. 70% fail

    If channel is buffered and not drained, goroutines may block or deadlock.

  2. Assuming append is atomic. 90% fail

    append is not atomic; it may read and update the slice header concurrently, causing corruption.