vm: eval cache mixes up script origins
Nobody has claimed this yet.
Assessment
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Newbie friendliness
- 45/100
- Issue type
- Bug
- Clarity
- Mostly clear
- Activity status
- Active
- Tech stack
- cpp, javascript, node.js
- Domain
- backend
Research direction
Reproduce the issue with the provided test.mjs under --experimental-vm-modules, then inspect deps/v8/src/codegen/compiler.cc around the "cache lookup key" comment. Trace the eval cache lookup and related tests to understand how script origins are represented. Done means the A/B/A assertion passes with compilation caching enabled while the existing no-compilation-cache behavior remains correct.
Written by the indexing model from the issue text.
Description
Bug report
- Node.js: v24.19.0, v26.8.1, v27.0.0-pre (local build)
- Platform: Microsoft Windows NT 10.0.26200.0 x64
- Subsystem: vm
// test.mjs
import assert from 'node:assert/strict';
import { Script } from 'node:vm';
const out = [];
function createScript(name) {
return new Script(`globalThis.eval('import("node:fs")')`, {
importModuleDynamically(specifier) {
out.push(name);
return import(specifier);
},
});
}
const a = createScript('A');
const b = createScript('B');
for (const script of [a, b, a]) {
await script.runInThisContext();
}
assert.deepEqual(out, ['A', 'B', 'A']);
Running this example as node --experimental-vm-modules test.mjs will give different wrong answers between v24 and v26 because V8 removed delayed caching some time during those releases. However, running with --no-compilation-cache will pass the test assertion.
The bug is with V8. In deps/v8/src/codegen/compiler.cc, around the "cache lookup key" comment, indirect eval uses kNoSourcePosition (-1), and the cache key does not distinguish the originating script. This allows identical eval source text from different scripts in the same realm to produce a false positive cache hit.
- Dominant language
- JavaScript
- Stars
- 122k
- Forks
- 37.4k
- Avg merge
- 4d 4h
- Merged PRs (30d)
- 276
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
More from nodejs/node
-
doc
Difficulty 2/5 1-3 hours Newbie friendliness 65/100
-
build
Difficulty 1/5 Under an hour Newbie friendliness 88/100
-
Difficulty 2/5 1-3 hours Newbie friendliness 84/100
-
Difficulty 1/5 Under an hour Newbie friendliness 90/100
-
feature request
Difficulty 2/5 1-3 hours Newbie friendliness 68/100
Similar issues
-
ai-observability bug team/ai-observability
Difficulty 2/5 1-3 hours Newbie friendliness 78/100
-
Difficulty 2/5 1-3 hours Newbie friendliness 68/100
AllTheMods/ATM-10-L#19 ·
-
Difficulty 2/5 1-3 hours Newbie friendliness 78/100
SignalK/n2k-signalk#345 ·
-
Difficulty 2/5 1-3 hours Newbie friendliness 84/100
-
Difficulty 1/5 1-3 hours Newbie friendliness 88/100
JuliaPluto/PlutoPlotly.jl#72 ·