Nested nav stacks are not destroyed when their root does

[4mp3R]

Ionic version: (check one with "x")
[ ] 1.x
[x] 2.x

I'm submitting a ... (check one with "x")
[x] bug report
[ ] feature request
[ ] support request => Please do not submit support requests here, use one of these channels: https://forum.ionicframework.com/ or http://ionicworldwide.herokuapp.com/

Current behavior:
When using nested navigation stacks, the children nav stacks are not destroyed when their root does.

Expected behavior:
All the children nav stacks along with the pages they contain should be destroyed when their root nav stack is destroyed.

Steps to reproduce:
Plunkr link: http://plnkr.co/edit/365N234EjkVepp1GQbhJ?p=preview

If my understanding is correct, the initial set of nav stacks should look as follows:

Component	Nav Controller Type	Nav Stack
AppComponent	Nav	[ HomePage ]
HomePage	Nav	[ TabsView ]
TabsView	Tabs	[ Tab1Component ], [ Tab2Component ] -> One nav stack per tab

You can see the stream observer in the Tab1Component printing console logs once a second.

When you click on the Change the root page button in the 1st tab,
the .setRoot(AltHomePage) is called on the application's root nav controller.

At this point I'd expect the only nav stack to be like this:

Component	Nav Controller Type	Nav Stack
AppComponent	Nav	[ AltHomePage ]

I would also expect the nested nav stacks to be destroyed along with the pages they contain.
However, we can observe that:

• The subscription made in the 1st tab remain active and reacts on new stream data
• The ionViewWillUnload() methods of the components in the nested nav controllers' stacks are not called
• The ngOnDestroy() hooks are called

So it seems like the components are actually destroyed from Angular's point of view, but not from Ionic's one.
Moreover, it seems like Ionic continues to keep track of the nested nav stacks (that should be removed at this point)
thus preventing the page instances from being released from memory.

This issue leads to memory leaks.
My impression is that some cleanup methods are not called in the Ionic's navigation system internals.
Anyways, I think there should be a way to release all the resources (nav controllers and relative pages) related to a nav stack.

Ionic info: (run ionic info from a terminal/cmd prompt and paste output below):

Your system information:

Cordova CLI: 6.4.0
Ionic Framework Version: 2.0.0
Ionic CLI Version: 2.1.13
Ionic App Lib Version: 2.1.7
Ionic App Scripts Version: 1.0.0
ios-deploy version: 1.9.0
ios-sim version: 5.0.8
OS: OS X El Capitan
Node Version: v6.5.0
Xcode version: Xcode 8.1 Build version 8B62

[tafax]

Any news for this (maybe) bug?

[ionitron-bot]

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