Playback build doesn't immediately end when netplay build is running next to it

[FluentCoding]

Expected Behavior

The main thread of the playback build should stop immediately when being closed.

Current Behavior

When closing the playback build while the netplay build is running next to it, it takes around 10 seconds for the process to stop. You can see this if you follow the steps below with a task manager. This issue originated from: project-slippi/slippi-launcher#231.

Steps to Reproduce

1. Open the netplay build (through configure netplay build in the slippi launcher e.g.)
2. Open the playback build
3. Close the playback build (and you will notice in the task manager that the process is still running for around 10 seconds until it closes itself, except for if you follow step 4 without waiting)
4. Close the netplay build (which results into both processes being stopped immediately)

Environment

Windows 10 Home 64-bit
Slippi Launcher to open both dolphin builds

Video

The included video shows the step to reproduce the issue in two ways, 1. with waiting for the playback build process to automatically end after closing it and 2. without waiting and closing the netplay build before the playback build process automatically ends.

2022-02-13.10-56-06.mp4