NodeJS : How to debug “EventEmitter memory leak detected. 11 listeners added”

Question

How can I debug my application which throw this error:

(node) warning: possible EventEmitter memory leak detected. 11 listeners added. Use emitter.setMaxList         


        

Answer 1

I ran into the same problem when testing React components using mocha and enzyme.

I was able to solve my problem by explicitly unmounting components after I had finished testing them.

The issue was that I was mounting components multiple times in my tests, which were then adding more listeners, until the number of listeners got to 11, and I got a warning.

I changed my test code by adding the rendered.unmount() line. This fixed the problem for me.

describe('', () => {

    it('renders', function () {
        const rendered = mount();
        assert.ok(rendered.find('path'));
        rendered.unmount();
    });
}