Limit the memory usage in Windows 10 WSL2

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Limit the memory usage

It was annoying that WSL2 was always eating up my poor RAM. The following solution worked. [Reference]

My distribution is:

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> wsl -l -v
  NAME            STATE           VERSION
* Ubuntu-18.04    Running         2

Create a configure file named .wslconfig in your user directory in Windows.

Open PowerShell as administrator, shutdown WSL2 and edit the file:

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> wsl --shutdown
> notepad "$env:USERPROFILE\.wslconfig"

For me the content is:

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[wsl2]
memory=2GB
swap=0

After these steps, the memory usage of my WSL2 never bothered me again.

Compact the virtual disk

This file always occupies a huge amount of space: %USERPROFILE%\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_*\LocalState\ext4.vhdx. It's because WSL2 won't actually release the space after files are deleted. The solution is to compact the virtual disk to reduce its size as follows. [Reference]

Open PowerShell as Administrator:

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> wsl --shutdown
> diskpart

# Replace <user> and <pkg> by yours. Must be a full path.
DISKPART> select vdisk file="C:\Users\<user>\AppData\Local\Packages\CanonicalGroupLimited.<pkg>\LocalState\ext4.vhdx"
  DiskPart successfully selected the virtual disk file.

# Compact and wait for several minutes
DISKPART> compact vdisk
  100 percent completed
  DiskPart successfully compacted the virtual disk file.

DISKPART> detach vdisk

Press Ctrl+C to exit DISKPART.

P.S. This didn't work for me (optimize-vhd is not found):

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> optimize-vhd -Path .\ext4.vhdx -Mode full