Enhancement: Cleaning up child node process after ending debug

[GregYankovoy]

• Dangling node process continues to run webpack-dev-server indefinitely
• Using existing AspNetCore libraries to end child process when debug is ended

Sourced from IIS Express Testing:
https://github.com/aspnet/AspNetCore/blob/3477daf3c4f530dff80f197e0642cb39a26fb07b/src/Servers/IIS/IntegrationTesting.IIS/src/ProcessTracker.cs

[EEParker]

Is this limited to windows only?

[GregYankovoy]

Yes, this cleanup activity is limited to Windows only (specifically Windows 8 & above). I have just confirmed the issue exists on linux as well (Ubuntu 18.04). I am not familiar with an aspnetcore solution for Linux.

I would obviously prefer to implement a universal solution, but I believe the problem is severe enough to warrant something OS-specific temporarily.

[agentschmitt]

Any chance that this will be integrated soon?
Working in Visual Studio it is anoying that the node process keeps running after stop debugging.
Would love to have this feature 👍

[EEParker]

I'm also assume this exists with the aspnet core npm runner: https://github.com/aspnet/AspNetCore/blob/master/src/Middleware/SpaServices.Extensions/src/Npm/NpmScriptRunner.cs

[EEParker]

FYI, I agree with the premise of this update. However, the more this library deviates from the SpaService.Extensions, the harder it will be to maintain. As of right now I can easily merge any upstream changes manually. If this is the only solution suggested within a few weeks, then I will merge it.

[EEParker]

TODO: investigate dotnet/corefx#34147

[EEParker]

Here is another topic that also kills POSIX child processes
dotnet/cli#10720

[EEParker]

I went a little different route, it is not as robust of a solution as the proposed implementation in this PR, but it should be cross platform.
https://github.com/EEParker/aspnetcore-vueclimiddleware/blob/master/src/VueCliMiddleware/Util/KillPort.cs

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