Debugger: Processes 'dotnet' and 'clrdbg' are still running after stopping debugging.

[ClaireKang]

Environment data

dotnet --info output:
VS Code version: 1.9.1
C# Extension version: 1.7.0
dotnet cli: 1.0.0-preview2-1-003177
OS: Windows 10 Enterprise Insider Preview
Build: 15032.1000.AMD64FRE.RS_ONECORE_BASE_BPT1.170207-1700_CLIENT_ENTERPRISE_EN-US_VL.VHDX
Scenarios: WSL Pipe

Steps to reproduce

1. Open attached folder
   app2.zip

2. Set a bp at the line of 12 (i++).

3. Press F5 to start debugging.

4. Remove the bp.

5. Press F5 to continue debugging.

6. Press Pause(F6) to break all. (The 'break all' has no effect )

7. Stop debugging

Expected behavior

1. The 'break all'(Can't format C# code #5) should work correctly.
2. Processes 'dotnet' and 'clrdbg' have stopped after stop debugging.

Actual behavior

1. The 'break all' has no effect
2. Processes 'dotnet' and 'clrdbg' are still running after stopping debugging.

Investigation

1. After the above steps, set a bp and continue F5 to start debugging, the debugging will become very slow.

[ClaireKang]

I tried to add more cores(4 cores), and the result is as follows:

1. Processes 'dotnet' and 'clrdbg' are still running after stopping debugging. And if I tried do the repro steps over and over, the number of the 'dotnet' and 'clrdbg' increase as illustrated below:
   

2. I've assigned 4 cores to the VM, and the problem of #investigation didn't reproduce until the 5th time I repeated the steps above