snapcraft overcommits CPUs in a multipass environment
Metadata
Current evaluation
Resolved by snapcore/snapcraft#2365 (commit c325c62ad), which reduced the conservative default Multipass CPU allocation to address host overcommit.
Resolution: closed resolved
Reason: The maintainer linked the resolution to snapcore/snapcraft#2365. Git history confirms merged commit c325c62ad, "multipass: change default CPU value (#2365)."
Evaluated by: mr-cal-bot
No scores available.
Issue body
On my relatively low-spec machine (mobile 2-core HT CPU, 8GB RAM) snapcraft allocates machines with 4 CPU threads and 2GB RAM and continues to use all the memory available when building the project.
I think there should be a minimum RAM : CPU ratio that snapcraft should implement (more like 1GB minimum per CPU thread).
Evaluation history
| Date | Model | Scores | Action | Summary |
|---|---|---|---|---|
| stealth/space-bunny-alpha | — | closed resolved | Resolved by snapcore/snapcraft#2365 (commit c325c62ad), which reduced the conservative default Multipass CPU allocation to address host overcommit. | |
| stealth/space-bunny-alpha | — | closed resolved | Fixed in merged PR canonical/snapcraft#2365 (commit c325c62ad), which replaced Multipass's default CPU allocation with a conservative value aligned with memory while retaining override guidance. | |
| stealth/space-bunny-alpha | — | closed resolved | Multipass CPU allocation was improved in #2273 (cbd1854d9); #2365 later adjusted the default CPU value. The history provides no evidence of the proposed RAM-per-CPU policy. | |
| qwen/qwen3.6-35b-a3b | — | — | Closed without resolution. The report identified snapcraft overcommitting CPUs and RAM in multipass environments, suggesting a 1GB per CPU thread minimum. No fix was implemented. | |
| qwen/qwen3.6-35b-a3b | — | — | Closed without resolution. The report of snapcraft overallocating CPUs and memory in multipass environments was abandoned due to inactivity. No fix was implemented. |
Update history
| Date | Change |
|---|---|
| created |
Related work
-
Likely Fixed By:
snapcore/snapcraft#2365
(confidence 100%)
The linked PR was merged as c325c62ad and changed the default Multipass CPU value.
Related issues
| Issue | Project | State | Summary | Similarity |
|---|---|---|---|---|
| #1792581 CPU max and override for multipass | snapcraft (launchpad) | closed | Resolved by snapcore/snapcraft#2273, commit cbd1854d9, which selected the best available CPU configuration for Multipass. | |
| #212 Incorrectly handling SNAPCRAFT_MAX_PARALLEL_BUILD_COUNT | craft-providers | open | SNAPCRAFT_MAX_PARALLEL_BUILD_COUNT not honored and Multipass instances hardcoded to 2 CPUs. Maintainer triaged; still unfixed in craft-providers (cpus=2 at multipass_provider.py:300), provider-side work split out to #531, snapcraft-side partly fixed in 8.4.4. |