go runtime_error ai_generated true

panic: close of nil channel

ID: go/panic-close-of-nil-channel

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-05-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.18 active — — —
1.22 active — — —

Root Cause

close() is called on a channel variable that was never initialized with make(), so it holds the nil zero value.

generic

中文

对一个从未用 make() 初始化的 channel 变量调用 close()，其值为 nil 零值。

Workarounds

  1. 95% success 
    Initialize the channel at declaration: ch := make(chan int). Never use var ch chan int without assignment if it will be closed.
  2. 93% success 
    Use a struct constructor that always makes the channel, e.g. func NewWorker() *Worker { return &Worker{jobs: make(chan Job)} }.

Dead Ends

Common approaches that don't work:

  1. 75% fail

    Skipping the close leaves the channel open forever, so receivers block indefinitely; the underlying logic bug remains.

  2. 85% fail

    Creating a fresh channel at close time means no other goroutine holds a reference to it; the close is meaningless.