memory-leak

This repo demonstrates a memory leak where after rendering and un-rendering a component that invokes a local helper, the helper will be retained in memory until the app exits.

App layout

The app implements a component called Thing that invokes a local helper, and also stores a WeakRef referencing that local helper in window.localHelperRef.

After rendering and un-rendering Thing, window.localHelperRef.deref() can be used to demonstrate that the local helper leaked.

Test repro

The app contains a single unit test that renders the component, then un-renders it, then checks the WeakRef.

Manual repro

To reproduce it manually and rule out any test instrumentation/timing issues as the cause of this, the dummy app is set up with a button that toggles the rendering of Thing. To reproduce the issue:

1. ember serve
2. Visit http://localhost:4200
3. Click the toggle button twice (once to render the component, then once to un-render it)
4. Open the devtool and go to Memory tab
5. Click the garbage collection button
6. Type window.localHelperRef.deref() in the console

You will see that the helper arrow function is still retained in memory. You can also replace step (6) with taking a heap snapshot and searching for Thing in the class filter to see that the component instance leaked as well (because the helper arrow function closes over it).