My node.js backend has a lot of mongoose.connection.useDb lines because it frequently needs to switch databases. Today I restarted my server and got this warnings:

MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 connected listeners added to [NativeConnection].

It took me some time to find a solution, and I found that by just adding mongoose.connection.removeAllListeners() the warning dissapears. What does this mean, and what exactly is an event? It feels like if I remove all listeners that the code that used those databases (like when I needed to create a model for a schema) shouldn't work anymore, but that isn't the case.