File handles remain open on Shipping Windows build after assets have finished loading

This developer has a game that they are targeting a Windows-based arcade machine for, but they noticed that while the game is running there are several hundreds or thousands of file handles left open after assets have already finished being read from disk.

I told them about the UsePakFile option, which will reduce these file handles to one, but they want to leave the assets as separate files on disk so they can update their game remotely more easily.

1. Using the launcher version, make a blank blueprint project with some assets and a level that uses those assets
2. In project settings > Maps & Modes, makes sure the Game Default Map is set to the map you created
3. In project settings > packaging settings, set the build configuration to "shipping" and set "use pak file" to false
4. From the file menu, choose Package Project > Win 64-bit, choose a folder to save the results in
5. After packaging has finished, open the folder and start the game executable.
6. Wait for the game to load completely
7. Open process explorer ([Link Removed])
8. In the process explorer list view, under Explorer.exe there should be an entry for the name of your game .exe. Under that there should be a UE4Game-Win64-Shipping.exe entry. Select this.
9. Ensure the lower pane is visible by pushing the "Show lower pane" button on the toolbar
10. In the lower pane, observe that although all file operations have finished, there are still file handles open for each asset
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