Initial notification when generating Heap Dump

[jaggernod]

Creating and processing a Heap Dump does freeze UI for a significant amount of time for large heap dumps.
It's 8 seconds for me during which the application is unresponsive.
Of course the users won't be affected by that but our QA will.

Do you think it is a good idea to show a Toast (or any other notification) when you start the process. Will make users more aware why app is unresponsive.

[pyricau]

That's an interesting idea. While it's not built in LeakCanary at the moment, you should be able to implement it easily.

1. Create a new implementation of HeapDumper similar to AndroidHeapDumper and setup the RefWatcher using that (look at the static methods in LeakCanary).
2. AndroidHeapDumper.dumpHeap() is called from a background thread. You could post to the main thread to tell your app to show some UI and block in dumpHeap() until that post is handled. Maybe wait for main thread idle.
3. Perform the heap dump.
4. Notify on the main thread that the heap dump has been performed.

I don't know if this is something we should build into LeakCanary or not, and I'm also not sure what the best sort of notification would be for that usage (notification, toast, adding a view to the hierarchy).. thoughts?

[pyricau]

I'm currently thinking of doing this only for the duration of the call to Debug.dumpHprofData().

However, before that we do a GC, and after that we perform the analysis in a separate process. The GC can take ~0.5s, while the heap dump can take ~3s. The analysis can take a minute.