GeezerVison

Copy link

Copy Markdown

Member

ShenHongFei reacted with confused emoji mcollina reacted with heart emoji

codebytere requested review from jasnell and joyeecheung August 16, 2026 16:44

@@            Coverage Diff             @@
##             main   #65329      +/-   ##
==========================================
- Coverage   90.13%   90.09%   -0.05%     
==========================================
  Files         752      752              
  Lines      251568   252348     +780     
  Branches    47270    47462     +192     
==========================================
+ Hits       226759   227355     +596     
- Misses      16168    16292     +124     
- Partials     8641     8701      +60     

jasnell approved these changes Aug 17, 2026

View reviewed changes

codebytere force-pushed the perf/bootstrap-fewer-builtins-without-snapshot branch from 5d49228 to 088f769 Compare August 17, 2026 08:01

aduh95 approved these changes Aug 17, 2026

View reviewed changes

                                                                                         confidence improvement accuracy (*)    (**)   (***)
misc/startup-core.js n=30 mode='process' script='benchmark/fixtures/empty.mjs'                           0.95 %      ±16.58% ±21.85% ±28.04%
misc/startup-core.js n=30 mode='process' script='benchmark/fixtures/import-builtins.mjs'                 0.60 %      ±11.57% ±15.25% ±19.56%
misc/startup-core.js n=30 mode='process' script='benchmark/fixtures/require-builtins.js'                 0.19 %      ±13.51% ±17.81% ±22.85%
misc/startup-core.js n=30 mode='process' script='test/fixtures/semicolon.js'                            -0.02 %      ±16.55% ±21.81% ±27.99%
misc/startup-core.js n=30 mode='process' script='test/fixtures/snapshot/typescript.js'                  -0.54 %       ±8.97% ±11.82% ±15.17%
misc/startup-core.js n=30 mode='worker' script='benchmark/fixtures/empty.mjs'                            3.74 %       ±9.02% ±11.89% ±15.26%
misc/startup-core.js n=30 mode='worker' script='benchmark/fixtures/import-builtins.mjs'                  1.08 %       ±8.87% ±11.69% ±15.00%
misc/startup-core.js n=30 mode='worker' script='benchmark/fixtures/require-builtins.js'                  1.37 %       ±8.86% ±11.67% ±14.98%
misc/startup-core.js n=30 mode='worker' script='test/fixtures/semicolon.js'                              4.08 %       ±9.20% ±12.13% ±15.56%
misc/startup-core.js n=30 mode='worker' script='test/fixtures/snapshot/typescript.js'                   -0.84 %       ±8.49% ±11.19% ±14.36%

Be aware that when doing many comparisons the risk of a false-positive
result increases. In this case, there are 10 comparisons, you can thus
expect the following amount of false-positive results:
  0.50 false positives, when considering a   5% risk acceptance (*, **, ***),
  0.10 false positives, when considering a   1% risk acceptance (**, ***),
  0.01 false positives, when considering a 0.1% risk acceptance (***)

mcollina approved these changes Aug 17, 2026

View reviewed changes

Sorry, something went wrong.

Uh oh!

There was an error while loading. Please reload this page.

---
duration_ms: 293.997
exitcode: 1
severity: fail
stack: |-
  node:internal/assert/utils:146
    throw error;
    ^

  AssertionError [ERR_ASSERTION]: These builtins are now no longer loaded before pre-execution.
  If this is intentional, remove them from `expected.beforePreExec`.

  --- These could be removed from expected.beforePreExec ---
  [
    'Internal Binding cjs_lexer',
    'Internal Binding encoding_binding',
    'NativeModule internal/blob',
    'NativeModule internal/data_url',
    'NativeModule internal/dns/utils',
    'NativeModule internal/encoding',
    'NativeModule internal/encoding/single-byte',
    'NativeModule internal/encoding/util',
    'NativeModule internal/mime',
    'NativeModule internal/modules/esm/assert',
    'NativeModule internal/modules/esm/get_format',
    'NativeModule internal/modules/esm/load',
    'NativeModule internal/modules/esm/loader',
    'NativeModule internal/modules/esm/module_job',
    'NativeModule internal/modules/esm/module_map',
    'NativeModule internal/modules/esm/resolve',
    'NativeModule internal/modules/esm/translators',
    'NativeModule internal/modules/typescript',
    'NativeModule internal/net',
    'NativeModule url'
  ]

  These builtins are now unexpectedly loaded at run time.
  If this is intentional, add them to `expected.atRunTime`.

  # Note: loading more builtins at run time can lead to startup performance regression.
  - Consider lazy loading builtins that are not used universally.

  --- These could be added to expected.atRunTime ---
  [
    'NativeModule internal/modules/esm/get_format'
  ]


  12 !== 0

      at Object.<anonymous> (d:\workspace\node-test-binary-windows-js-suites\node\test\parallel\test-bootstrap-modules.js:264:8)
      at Module._compile (node:internal/modules/cjs/loader:1937:14)
      at Module._extensions..js (node:internal/modules/cjs/loader:2077:10)
      at Module.load (node:internal/modules/cjs/loader:1659:32)
      at Module._load (node:internal/modules/cjs/loader:1451:12)
      at wrapModuleLoad (node:internal/modules/cjs/loader:261:19)
      at Module.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:154:5)
      at node:internal/main/run_main_module:33:47 {
    generatedMessage: false,
    code: 'ERR_ASSERTION',
    actual: 12,
    expected: 0,
    operator: 'strictEqual',
    diff: 'simple'
  }

  Node.js v27.0.0-pre
...

codebytere force-pushed the perf/bootstrap-fewer-builtins-without-snapshot branch from 088f769 to 0d3b8a7 Compare August 18, 2026 09:18

aduh95 reviewed Aug 18, 2026

View reviewed changes

codebytere force-pushed the perf/bootstrap-fewer-builtins-without-snapshot branch from 0d3b8a7 to f95b3c7 Compare August 18, 2026 14:13

codebytere requested review from aduh95, jasnell and mcollina August 19, 2026 08:52

jasnell approved these changes Aug 20, 2026

View reviewed changes

aduh95 reviewed Aug 20, 2026

View reviewed changes

aduh95 reviewed Aug 20, 2026

View reviewed changes

codebytere force-pushed the perf/bootstrap-fewer-builtins-without-snapshot branch from f95b3c7 to 0cc532a Compare August 20, 2026 12:39

legendecas approved these changes Aug 20, 2026

View reviewed changes

misc/startup-core.js mode='process' (snapshot), all scripts                       ±0.5 %  n.s.

                                               with snapshot     --no-node-snapshot
startup-cli-version  eslint --version         -0.14 %  n.s.     +1.70 %  ***
                     npm --version            -0.00 %  n.s.     +0.69 %  ***
                     npx --version            +0.11 %  n.s.     +0.80 %  **
                     corepack --version       -0.19 %  n.s.     +3.21 %  ***
require-builtins.js (start -> exit)           -0.08 %  n.s.     +1.97 %  ***
import-builtins.mjs                           +0.19 %  n.s.     +0.13 %  n.s.
empty CJS entry                               +0.04 %  n.s.    +10.59 %  ***

avivkeller approved these changes Aug 21, 2026

View reviewed changes

71 checks passed

Contexts that are not deserialized from the built-in snapshot -- worker
threads, and the main context of embedders that create their own
isolate or of `node --no-node-snapshot` -- compile (with the code cache
at best) every builtin the bootstrap touches, so each eagerly required
builtin is startup time (~0.15-0.4 ms apiece). A number of them are only
required eagerly so that they end up in the snapshot, or for features
the bootstrap path never uses.

Load lazily what those paths do not need:

- is_main_thread.js: preload util, url, the ESM loader (translators,
  resolver, module_job/map, source maps, node:module, vm modules, mime,
  data_url, the TypeScript stripper), internal/blob and
  internal/dns/utils only while building a snapshot; they load on first
  use otherwise.
- fs: internal/blob (+ internal/encoding and its tables) is only used
  by fs.openAsBlob().
- internal/url: internal/data_url (+ internal/mime) is only used by the
  Buffer-returning file URL helpers.
- internal/process/execution, the CommonJS loader, esm/translators and
  esm/load: the TypeScript stripper and data: URL helpers are only
  needed for TypeScript sources / data: URLs.
- pre_execution: internal/dns/utils (+ internal/net) is only needed up
  front to validate an explicit --dns-result-order or to register the
  resolver's snapshot serializer; the default order becomes the
  variable's initializer.
- internal/worker: event_loop_utilization and error_serdes are only
  needed once a sub-worker's ELU is read or it reports an error.
- worker_threads: `locks` is defined lazily, like util's lazy exports.

Main-thread startup with the snapshot is unchanged (the same modules
are preloaded into it; the bootstrap-modules test lists are adjusted).
A bare worker compiles 95 -> 83 builtins (cold start -5%); without the
snapshot an empty CommonJS entry point compiles 76 -> 59 builtins and an
empty ES module entry point 76 -> 69.

Signed-off-by: Shelley Vohr <[email protected]>
PR-URL: #65329
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Chengzhong Wu <[email protected]>
Reviewed-By: Aviv Keller <[email protected]>

Contexts that are not deserialized from the built-in snapshot -- worker
threads, and the main context of embedders that create their own
isolate or of `node --no-node-snapshot` -- compile (with the code cache
at best) every builtin the bootstrap touches, so each eagerly required
builtin is startup time (~0.15-0.4 ms apiece). A number of them are only
required eagerly so that they end up in the snapshot, or for features
the bootstrap path never uses.

Load lazily what those paths do not need:

- is_main_thread.js: preload util, url, the ESM loader (translators,
  resolver, module_job/map, source maps, node:module, vm modules, mime,
  data_url, the TypeScript stripper), internal/blob and
  internal/dns/utils only while building a snapshot; they load on first
  use otherwise.
- fs: internal/blob (+ internal/encoding and its tables) is only used
  by fs.openAsBlob().
- internal/url: internal/data_url (+ internal/mime) is only used by the
  Buffer-returning file URL helpers.
- internal/process/execution, the CommonJS loader, esm/translators and
  esm/load: the TypeScript stripper and data: URL helpers are only
  needed for TypeScript sources / data: URLs.
- pre_execution: internal/dns/utils (+ internal/net) is only needed up
  front to validate an explicit --dns-result-order or to register the
  resolver's snapshot serializer; the default order becomes the
  variable's initializer.
- internal/worker: event_loop_utilization and error_serdes are only
  needed once a sub-worker's ELU is read or it reports an error.
- worker_threads: `locks` is defined lazily, like util's lazy exports.

Main-thread startup with the snapshot is unchanged (the same modules
are preloaded into it; the bootstrap-modules test lists are adjusted).
A bare worker compiles 95 -> 83 builtins (cold start -5%); without the
snapshot an empty CommonJS entry point compiles 76 -> 59 builtins and an
empty ES module entry point 76 -> 69.

Signed-off-by: Shelley Vohr <[email protected]>
PR-URL: #65329
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Chengzhong Wu <[email protected]>
Reviewed-By: Aviv Keller <[email protected]>