Support inspecting widget tree of multi engine

[hyiso]

Currently, when using flutter attach, the widget tree in Flutter Inspector page only shows first engine's widget tree, we can't choose to see widget tree of other engine.

[CoderDake]

hi @hyiso what do you mean by other "engine"?
If possible could you post some code here to help us reproduce what you are experiencing?

[hyiso]

In my case, there are two Flutter Engines exist at the same time.

The first Flutter Engine shows one Flutter page, and the second Flutter Engine shows another Flutter page

I want to use devtools' inspector page to inspect the widget tree of the second Flutter Engine, but the inspector page only shows the first Flutter Engine's widget tree

I have no idea how to select the second Flutter Engine to inspect

[kenzieschmoll]

DevTools can only connect to a single Flutter app at a time. If you are running a separate flutter app, this will have its own instance of DevTools to debug with.

How are you opening DevTools?

• If you are running both of your flutter apps from Command line, each app will have a unique link to DevTools.
• If you are running both of your flutter apps from VS code, when you switch debug sessions, you'll be able to open DevTools pages for the debug session that is selected. If this is not possible, there may be a bug in the Dart Code VS Code extension @DanTup

[hyiso]

These two engines are in one app, in add2app scenario

The DevTools inspector page is opened in browser from VS Code after running flutter attach

There is no other debug session that I can found to select

[DanTup]

I'm not very familiar with add2app. When we say "two engines" here, do we mean "two Dart VMs" or a single VM with multiple isolates?

If there are two VMs it seems like there should be two VM Service URIs and you could "attach" to each of them from VS Code to get two sessions, although it also feels odd to need two VMs in a single app for two views.

[hyiso]

These two engines are created via FlutterEngineGroup, I have not seen any option to select session from VS Code when running flutter attach and opening DevTools

There was only one VM service URI printed to console when entering Flutter page.

The reason why we need two engines is irrelevant here

[nt4f04uNd]

There is a similar scenario with ContentProvider in my Flutter plugin, which I described here nt4f04uNd/android_content_provider#16 (comment)

[ultraon]

I have the same issue. I use add-to-app with a Multi-engine approach/flavor, see https://docs.flutter.dev/add-to-app/multiple-flutters. So, I have android app with 5 bottom bar tabs, 2 of them are FlutterFragments, when I use flutter attach command, I have a properly worked debugger, but when I use Flutter Inspector it shows me the very first Flutter Engine.
As I understand, internally it works as one DartVM and multiple isolates that correlates to multiple FlutterEngines created on the native Android app side.
There is no ability to switch/reconnect Flutter Inspector to the 2nd FlutterEngine in the same android application.