EventEmitter memory leak with socket bind #30209

• Version: v8.16.0 and greater
• Platform: MacOS
• Subsystem: dgram socket

When binding to a broadcast socket using-

const doSocketBind = () => {
    this.socket.bind(broadcastPort, undefined, () => {
        console.log('Success');
    });
};

And retrying the bind after a failure-

this.socket.on('error', (err: Error) => {
    if (err['code'] === 'EADDRINUSE') {
        setTimeout(() => {
            doSocketBind();
        }, 5000);
    }
});

After a few failures I receive this message-

(node:68039) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 listening listeners added. Use emitter.setMaxListeners() to increase limit

For example, if something else has bound to the same broadcast port and has locked the port.

The issue is caused by-

arguments[arguments.length - 1] is intended to be the callback. In the case of a failure, the callback doesn't execute and the callback remains in the event queue waiting to be executed. If there are 10 bind failures the callback will execute 10 times after being able to successfully bind in the 11th retry.

A workaround-

Define the callback as a named function and remove the callback if an error is encountered.

this.socket.on('error', (err: Error) => {
    this.socket.removeListener('listening', onSocketBind);

    if (err['code'] === 'EADDRINUSE') {
        setTimeout(() => {
            doSocketBind();
        }, 5000);
    }
});