how to clean up FlutterEngine

[Jim Xu]

hi, recently, I need to lazy start FlutterEngine, and clean up it on demand. I did it as following:

1. set all plugin's methodChannel as nil

2. dealloc all FlutterViewController

3. Underlying the Engine, I set the leak_vm setting as false, so it will not keep dart VM

4. At last, I can see FlutterEngine is dealloced, DartVM are deconstructed, Dart Isolates, DartVMData are also deconstructed. However, from the instruments or memory graph, there still are 30M memory persisted. I guessed part of them could be code/text segments of Flutter.framework, but I am not sure. Can anybody give a more reasonable explanation? Following is the screenshot of instrument, according the timestamp, it seems the flutter library has dealloced all the memory. Thanks in advance.

[Jim Xu]

attach the image again:

 

[Jim Xu]

Can anybody help? It annoyed me so much:)