Issues with Node.js EventEmitter memory leaks when handling multiple concurrent streams
I'm working on a project and hit a roadblock. I'm testing a new approach and I'm working on a Node.js application that uses the `EventEmitter` class extensively to handle multiple concurrent data streams. However, I'm encountering a memory leak issue. The application is built with Node.js v16.14.0 and uses the `stream` module to process incoming data. After running the application for a few hours, I notice that the memory usage keeps increasing, and I'm eventually getting the warning: `MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 error listeners added to [YourEmitter]. Use emitter.setMaxListeners() to increase limit`. I've tried several things to mitigate this issue. First, I checked the number of event listeners being attached. Here's a snippet of my code: ```javascript const EventEmitter = require('events'); const { Readable } = require('stream'); class MyEmitter extends EventEmitter {} const myEmitter = new MyEmitter(); myEmitter.on('data', (chunk) => { // process the chunk }); function handleStream(dataStream) { dataStream.on('data', (chunk) => myEmitter.emit('data', chunk)); } const stream1 = Readable.from(['data1', 'data2']); const stream2 = Readable.from(['data3', 'data4']); handleStream(stream1); handleStream(stream2); ``` In this case, I'm attaching data listeners for multiple streams, which I suspect may be causing the memory leak. I also added `myEmitter.setMaxListeners(20);` but that didn’t resolve the issue. The listeners keep piling up, and I also noticed that the event emitter does not seem to clean up the references to the old listeners once they are no longer needed. Additionally, I tried using `removeListener` to clean up after processing, but the memory usage still climbs. For example, I attempted this after processing each chunk: ```javascript myEmitter.removeListener('data', callbackFunction); ``` However, the callback function references don't seem to match up correctly, leading to confusion. What steps can I take to effectively manage event listeners in this scenario and prevent memory leaks? Are there any best practices I should be following when working with multiple streams and the EventEmitter? I'm working on a web app that needs to handle this. Is there a better approach? Any advice would be much appreciated. Thanks for taking the time to read this! My team is using Javascript for this web app. Any examples would be super helpful.