fix(core): Resolve host data paths once per expression evaluation by looorent · Pull Request #42571 · n8n-io/n8n

looorent · 2026-10-29T12:37:14Z

Summary

Reading an array from an expression parameter could repeat the same calculation for every element and cause QuickJS to time out. This PR reuses resolved host values within each evaluation.

The fix applies to both QuickJS and isolated-vm.

Why

Consider an ids parameter that contains:

{{ $input.all().map(item => item.json.id) }}

Reading {{ $parameter.ids }} looks simple. But the runtime reads array elements on demand. Each read used to resolve the path from the root, which could run the entire map() again.

The array is now resolved once and reused while its elements are read.

Related Linear tickets, Github issues, and Community forum posts

https://linear.app/n8n/issue/CET-540

Review / Merge checklist

I have seen this code, I have run this code, and I take responsibility for this code.
PR title and summary are descriptive. (conventions)
Tests included.
PR Labeled with Backport to Beta, Backport to Stable, or Backport to v1 (if the PR is an urgent fix that needs to be backported)

A parameter value can hold an expression, so reading it can evaluate a nested expression. Paths such as `$node["A"].parameter.ids` and `$item(0).$parameter.ids` reach that value below the first two steps, so the resolver read it again for each array element. Cache the path down to the parameter value for `$parameter` and `$node[name].parameter`, also under `$item(i)`. Keep the default depth for other paths.

cubic-dev-ai

No issues found across 8 files

Confidence score: 5/5

Automated review surfaced no issues in the provided summaries.
No files require special attention.

_{Shadow auto-approve: would auto-approve. Bounded performance fix: caches resolved host data path prefixes once per expression evaluation in QuickJS and isolated-vm, avoiding repeated re-evaluation of parameter expressions; covered by unit and integration tests.

View guided diff | Turn on auto-fix | Re-trigger cubic}

codecov · 2026-10-29T12:52:56Z

Bundle Report

Changes will increase total bundle size by 383 bytes (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
editor-ui-esm	61.61MB	383 bytes (0.0%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: editor-ui-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`assets/app-*.js`	383 bytes	9.15MB	0.0%
`assets/worker-*.js`	3.41MB	3.43MB	17518.09% ⚠️
`assets/worker-*.js`	-3.41MB	19.46kB	-99.43%
`assets/src-*.js`	-74 bytes	64 bytes	-53.62%
`assets/src-*.js`	74 bytes	138 bytes	115.62% ⚠️

codecov · 2026-10-29T12:57:53Z

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

n8n-assistant · 2026-10-29T13:08:00Z

PR review overview

Based on ownership of the 8 changed files in this PR:

Ownership	Files owned	Share	Source code	Test files	Misc
@n8n-io/core-execution	8	100%	+141 / -157	+471 / -3	+0 / -0
Total	8	100%	+141 / -157	+471 / -3	+0 / -0

Co-Authored-By: Kimi K3.1 Pro <noreply@moonshot.ai>

despairblue

added more tests, rests looks nice, good work

cubic-dev-ai

0 issues found across 2 files (changes from recent commits).

Confidence score: 5/5

Automated review surfaced no issues in the provided summaries.
No files require special attention.

_{Shadow auto-approve: would not auto-approve. Auto-approval skipped because cubic reviewed only this push, not the earlier force-push. Comment @cubic review to review the whole pull request.

View guided diff | Turn on auto-fix | Re-trigger cubic}

n8n-assistant · 2026-10-29T15:36:43Z

Created backport PR for release-candidate/2.46.x:

fix(core): Resolve host data paths once per expression evaluation (backport to release-candidate/2.46.x) #42620 with remaining conflicts!

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin backport-42571-to-release-candidate/2.46.x
git worktree add --checkout .worktree/backport-42571-to-release-candidate/2.46.x backport-42571-to-release-candidate/2.46.x
cd .worktree/backport-42571-to-release-candidate/2.46.x
git reset --hard HEAD^
git cherry-pick -x d50a44698bfb08f368dad62bb9fde7e2947da396
git push --force-with-lease

n8n-assistant · 2026-10-29T15:36:58Z

Created backport PR for release-candidate/2.45.x:

fix(core): Resolve host data paths once per expression evaluation (backport to release-candidate/2.45.x) #42621 with remaining conflicts!

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin backport-42571-to-release-candidate/2.45.x
git worktree add --checkout .worktree/backport-42571-to-release-candidate/2.45.x backport-42571-to-release-candidate/2.45.x
cd .worktree/backport-42571-to-release-candidate/2.45.x
git reset --hard HEAD^
git cherry-pick -x d50a44698bfb08f368dad62bb9fde7e2947da396
git push --force-with-lease

n8n-assistant · 2026-10-29T16:46:33Z

Created backport PR for release-candidate/2.46.x:

fix(core): Resolve host data paths once per expression evaluation (backport to release-candidate/2.46.x) #42635 with remaining conflicts!

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin backport-42571-to-release-candidate/2.46.x
git worktree add --checkout .worktree/backport-42571-to-release-candidate/2.46.x backport-42571-to-release-candidate/2.46.x
cd .worktree/backport-42571-to-release-candidate/2.46.x
git reset --hard HEAD^
git cherry-pick -x d50a44698bfb08f368dad62bb9fde7e2947da396
git push --force-with-lease

…2571) Co-authored-by: Danny Martini <danny@n8n.io> Co-authored-by: Kimi K3.1 Pro <noreply@moonshot.ai> (cherry picked from commit d50a446)

looorent requested review from despairblue and ivov and removed request for despairblue October 29, 2026 12:38

looorent added Backport to Beta Backport to Stable labels Oct 29, 2026

looorent added 2 commits October 29, 2026 13:42

fix(core): Resolve host data paths once per expression evaluation

d69591c

cubic-dev-ai Bot reviewed Oct 29, 2026

View reviewed changes

looorent marked this pull request as ready for review October 29, 2026 12:50

looorent force-pushed the cet-540-a6-find-why-quickjs-times-out-on-simple-expressions-in-the branch from 5bf827c to 5736079 Compare October 29, 2026 12:50

n8n-assistant Bot added the cla-signed label Oct 29, 2026

test(core): strengthen host resolver coverage

ff79d92

Co-Authored-By: Kimi K3.1 Pro <noreply@moonshot.ai>

despairblue approved these changes Oct 29, 2026

View reviewed changes

cubic-dev-ai Bot reviewed Oct 29, 2026

View reviewed changes

looorent enabled auto-merge October 29, 2026 14:50

looorent added this pull request to the merge queue Oct 29, 2026

Merged via the queue into master with commit d50a446 Oct 29, 2026
81 checks passed

looorent deleted the cet-540-a6-find-why-quickjs-times-out-on-simple-expressions-in-the branch October 29, 2026 15:35

n8n-assistant Bot mentioned this pull request Oct 29, 2026

fix(core): Resolve host data paths once per expression evaluation (backport to release-candidate/2.46.x) #42620

Closed

4 of 7 tasks

n8n-assistant Bot mentioned this pull request Oct 29, 2026

fix(core): Resolve host data paths once per expression evaluation (backport to release-candidate/2.45.x) #42621

Closed

4 of 7 tasks

looorent added Backport to Beta and removed Backport to Beta Backport to Stable labels Oct 29, 2026

n8n-assistant Bot mentioned this pull request Oct 29, 2026

fix(core): Resolve host data paths once per expression evaluation (backport to release-candidate/2.46.x) #42635

Merged

4 of 7 tasks

n8n-assistant Bot mentioned this pull request Oct 30, 2026

chore: Resolve master→3.x sync conflict #42656

Merged

3 of 6 tasks

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fix(core): Resolve host data paths once per expression evaluation - #42571

fix(core): Resolve host data paths once per expression evaluation#42571
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Related Linear tickets, Github issues, and Community forum posts

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