Microsoft has announced a significant upgrade to Windows Subsystem for Linux. The second version of WSL has a new architecture which dramatically improves the system performance. WSL 2 is full system call compatible, i.e., you will be able to run more Linux Apps. All this without any compromise on the user experience.
WSL 2 with a real Linux Kernel announced
WSL 2 now ships with a Linux Kernel. It makes full system call possible and can run ELF64 Linux binaries on Windows.
How fast is WSL 2 compared to WSL 1
Microsoft claims WSL 2 is 20x faster compared to WSL 1 when unpacking a zipped tarball, and around 2-5x faster when using git clone, npm install and cmake on various projects. However, in the end, it will depend on what you are doing on the Linux subsystem.
Full System Call Compatibility
In WSL 1, Microsoft created a translation layer. This layer interprets system calls and allows them to work on the Windows NT kernel. However, it was limited, and now that WSL 2 has its own Linux Kernel. Apps like Docker, Fuse which needs a pure Linux Kernel. Moving forward, new features will be available right away when the update to Kernel is rolled out.
Do the current Distros need to upgrade?
They can either run as WSL 1 distro or WSL 2 distro. You can upgrade or downgrade anytime and even run WSL 1 and WSL 2 side by side. The most significant change is that with a real Linux Kernel, developers or consumers can enjoy the real Linux experience.
Initial builds of WSL 2 will be available through the Windows Insider program by the end of June 2019.