go runtime_error ai_generated true

恐慌：运行时错误：索引超出范围 [5]，长度为 5（闭包捕获）

panic: runtime error: index out of range [5] with length 5 (closure capture)

ID: go/goroutine-slice-iteration-closure

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80%修复率
88%置信度
0证据数
2024-11-01首次发现

版本兼容性

版本状态引入弃用备注
1.0 active — — —
1.22 active — — —

根因分析

goroutine 闭包通过引用捕获循环变量，导致 goroutine 在循环后执行时索引值意外。

English

A goroutine closure captures a loop variable by reference, leading to unexpected index values when the goroutine executes after the loop.

generic

解决方案

  1. 95% 成功率 Copy loop variable to a local variable inside the loop 
    for i := 0; i < 5; i++ {
    i := i
    go func() {
        fmt.Println(i)
    }()
}
  2. 95% 成功率 Pass the value as an argument to the goroutine 
    for i := 0; i < 5; i++ {
    go func(val int) {
        fmt.Println(val)
    }(i)
}

无效尝试

常见但无效的做法:

  1. Using a sleep inside the loop to 'wait' for goroutines 80% 失败

    Does not fix closure capture; goroutines still see final index.

  2. Using a different variable name inside the loop without copying 70% 失败

    All goroutines still reference the same variable.