MaxListenersExceededWarning when using signal

[axetroy]

Bug Description

When a signal is passed to fecth, an abort event is listened for.

However, when requesting a result, there is no overflow listener for the abort event. This means that if the same signal is used for multiple requests, there is a risk of signal leakage, and Node.js continuously outputs warnings.

(node:14604) MaxListenersExceededWarning: Possible EventTarget memory leak detected. 9053 abort listeners added to [AbortSignal]. Use events.setMaxListeners() to increase limit

Reproducible By

        const response = await fetch(requestUrl, {
            method,
            headers: requestHeaders,
            dispatcher: downloadAgent,
            signal
        })

Expected Behavior

The abort event listener should be canceled when the request ends.

Logs & Screenshots

Environment

Additional context

[KhafraDev]

The abort event listener should be canceled when the request ends.

The request ending does not signify the end of the AbortSignal's lifetime. The spec allows you to abort up to the point where you consume the body.

const response = await fetch(requestUrl, {
    method,
    signal
})

// request ended
signal.abort()
await response.text()
// error thrown

Not to say that this isn't a bug, but unfortunately someone will shove this into Claude without doing their due diligence and create a... misinformed PR.

[axetroy]

The abort event listener should be canceled when the request ends.

The request ending does not signify the end of the AbortSignal's lifetime. The spec allows you to abort up to the point where you consume the body.

const response = await fetch(requestUrl, {
method,
signal
})

// request ended
signal.abort()
await response.text()
// error thrown
Not to say that this isn't a bug, but unfortunately someone will shove this into Claude without doing their due diligence and create a... misinformed PR.

You're right. Receiving a response only means the server has sent back the headers—the body hasn't been consumed yet, so you still need to listen for an abort.

However, should the listener be destroyed once the body has finished consuming the data?