Angular not releasing memory on component destroy

I have two components: ComponentList and ComponentDetail. The way it works right now is that a user will choose one from the list and it would redirect it to the ComponentDetail that calls an API and gets a large data set for an observable. Now, the problem that I am encountering is that when I go back to the ComponentList, the memory that is used by the ComponentDetail is not being garbage collected upon onDestroy. It goes down after ten minutes but if forced GC’d from the devtools it would release the memory space quickly. I am not sure which is causing it to take a long time to be collected automatically, is there something I could do to make the garbage collection happen right after the ngOnDestroy?

Answer

(V8 developer here.)

Just to confirm what commenters have said: there is no way to force immediate garbage collection, and you shouldn’t have to worry about it. When your app makes an object eligible for garbage collection (by dropping all references to it), then the garbage collector will free it the next time it runs, which could be fairly soon, or it could take a while. The reason is simply that finding dead objects is an expensive operation, so V8 (and, of course, other JS engines just the same) is very carefully tuned to find a good balance between freeing memory reasonably quickly (especially when there is memory pressure) and not spending too much CPU time on doing so.

In the case at hand, it is unsurprising that when you allocate a single large object (or group of objects), and then drop all references to it, and then just wait, it’ll take a while for the next GC cycle to kick in; whereas if you continued to allocate large objects, then all that allocation activity would be a strong hint for the GC to kick in and go looking for garbage it can free.