Docker VMM Public Beta Released, Refreshing the Virtualization Layer

Docker announced the public beta of “Docker VMM,” a newly developed, high-performance hypervisor for containers, on August 12, 2026. It supports both Windows and macOS platforms and is available in the latest version, “Docker Desktop v4.86.” According to a report by Publickey’s jniino, the official release is scheduled for the end of October 2026. At that time, it will become the default virtualization engine in Docker Desktop for Windows, Mac, and Linux.

Docker Desktop’s Virtualization Architecture

Docker Desktop is a tool that allows for easy setup and use of Docker container environments on Windows, Mac, and Linux. Internally, this tool adopts a two-layer structure: it launches a virtual machine on the host operating system, and containers run within that virtual machine. Containers isolate processes using OS-level virtualization technology, but since Windows and macOS cannot natively run Linux containers, a mechanism that relays through a virtual machine is necessary.

Previously, the hypervisors forming the foundation of this virtual machine used different solutions for each platform. The Windows version used Microsoft’s Hyper-V, while the macOS version used Docker’s own proprietary previous-generation Docker VMM. Hyper-V is a full-fledged virtualization platform for Windows Server, but for Docker Desktop’s use cases, reports of overhead issues and stability problems were occasionally seen. The macOS version of Docker VMM also functioned basically, but there was room for improvement in performance and compatibility.

Technical Improvements in the New Hypervisor

Docker explains that this overhaul has achieved the following technical improvements with the new Docker VMM:

Faster Startup: The overall startup speed for containers has increased. In development workflows where containers are frequently created and destroyed, shorter startup times directly contribute to increased productivity.

Improved File I/O: This is a particularly noteworthy point. File sharing between the host operating system and containers is dramatically faster. It’s common practice in Docker Desktop to mount host directories for use within containers, and performance here directly impacts the development experience. Docker states that improvements can be felt with every build execution.

Improved Memory Management: Containers now return memory they were using to the host operating system when they enter an idle state. Previously, cases were observed where containers continued to consume a certain amount of memory, leading to resource exhaustion on the host side. By releasing memory when idle, memory efficiency in environments operating multiple containers simultaneously is expected to improve.

Significance of Providing a Proprietary

Hypervisor for Windows

This overhaul on Windows carries greater significance. It marks Docker’s first provision of a proprietary, in-house developed hypervisor, eliminating the previous dependency on Hyper-V. Docker positions this as enabling them to directly guarantee the performance and stability they offer.

What’s particularly noteworthy is the simultaneous achievement of performance and isolation. In Windows environments, container execution based on WSL (Windows Subsystem for Linux) and execution based on Hyper-V have coexisted. WSL delivers high performance, but its isolation as a virtual machine was incomplete. Conversely, Hyper-V provides complete isolation but has high overhead. The new Docker VMM integrates the strengths of both, aiming to provide optimized performance while realizing a completely isolated virtual machine.

Upgrade Path and Future Roadmap

Existing users can utilize the new Docker VMM by upgrading to Docker Desktop v4.86. On macOS, environments that previously used Docker VMM will automatically update to the latest version. On Windows, a manual operation to switch to the latest Docker VMM via the settings screen is required. When migrating from Hyper-V to the new hypervisor, verifying compatibility will likely become a future task.

The official release is targeted for the end of October 2026. At that time, it is planned to become the default virtualization engine on all platforms. During the public beta period, bug reports and feedback will be gathered to finalize stability and performance.

Editorial Opinion

Short-term Impact The public beta release of Docker VMM will directly change the development experience for Docker Desktop users. The dramatic speedup in file I/O and memory release at idle will be particularly effective in development environments running numerous containers. Especially on macOS, poor file-sharing performance has been a long-standing issue, and its resolution could significantly alleviate developer dissatisfaction. During the approximately two-month beta period before the official release, identifying compatibility bugs will be crucial.

Long-term Perspective The break from Hyper-V dependency is a strategic turning point for Docker on the platform level. By controlling its own virtualization layer, future feature expansion and consistent behavior across operating systems become possible. Placing the virtualization foundation under its own control is also seen as a foundational step for broader expansion into the container ecosystem, such as integration with cloud environments and edge container deployment.

Question from the Editorial Team If the official release makes this the default engine, the possibility of impacting existing CI/CD pipelines and development environments cannot be denied.

References

• “Docker社、コンテナ向けの高性能な新ハイパーバイザ「Docker VMM」パブリックベータ公開”, by jniino — Publickey, 2026-08-19T17:43:24.000Z (ARR)
• Source URL: https://www.publickey1.jp/blog/26/dockerdocker_vmm.html