Clone, a small Rust VMM, forks VMs in under 20ms via CoW
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We needed a secure, multi-tenant way to offer shell accounts to users, but most VMMs were using too much memory and containers are unsafe. With clone, VMs are now more memory efficient than containers in most cases.Since many other projects on HN looked like they were doing this too, open sourcing this was the right thing to do.Feel free to use in whole or in part as you see fit!
HN · launched Apr 19, 2026 · 11 upvotes (top 38%) · 0 views
Niche: os virtualization and vm management software · 61 launches, 3 in the last 7 days ▼ -57% · Explore this niche →
Category and tags
- Horizontal
- Dev tools
- Developer
- Not AI
- Hobby / open-source project
Visit website ↗ Source listing ↗
More like this: all 61 launches in os virtualization and vm management software →
Could you build this?
No Writing a custom hypervisor/VMM in Rust that leverages KVM and memory copy-on-write fork mechanics requires deep operating system and hypervisor engineering expertise.
What it would actually take: The implementation relies on Rust interfaces to Linux KVM (`/dev/kvm`), low-level paging control, and `userfaultfd` or custom page table manipulation to implement fast Copy-on-Write (CoW) memory forks under 20ms. The critical complexities include handling vCPU registers, restoring hypervisor state, managing virtio device resets, and preventing guest escape vulnerabilities. This requires senior systems/kernel engineers with expertise in virtualization internals.
Discussion
3 comments analyzed.
Competitors mentioned: Firecracker
Concerns raised: Template drift over time with warm snapshots, Memory overhead claims may be inaccurate vs Firecracker snapshots, Cold boot performance not optimized
Feature requests: Better method for handling security updates without forced reboots, Patch warm templates in place without losing memory-sharing
Competitors
Other products that read as similar to this one : 289 launches clear the similarity bar, closest 8 shown.
Attention rank: #120 of 290 (itself plus its competitors, highest first, normalized so YC and Product Hunt are compared fairly).
Launched 170 days after the earliest competitor.
- Sub-millisecond VM sandboxes using CoW memory forking · hn · 2026-03-17 · 311 upvotes · similarity 0.59
- Shrouded, secure memory management in Rust · hn · 2026-03-23 · 5 upvotes · similarity 0.56
- Sofka · hn · 2026-08-19 · 5 upvotes · similarity 0.53
- Cygnus · hn · 2026-07-25 · 8 upvotes · similarity 0.49
- machine0 · hn · 2026-06-15 · 96 upvotes · similarity 0.49
- We built a <60ms, open-source alternative to E2B using RustVMM and KVM · hn · 2026-04-22 · 7 upvotes · similarity 0.48
- Numax · hn · 2026-06-16 · 6 upvotes · similarity 0.47
- Vpod · hn · 2026-06-17 · 12 upvotes · similarity 0.46
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