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Title: node-api: use fast properties in node_api_create_object_with_properties by colinhacks · Pull Request #66470 · nodejs/node · GitHub

Open Graph Title: node-api: use fast properties in node_api_create_object_with_properties by colinhacks · Pull Request #66470 · nodejs/node

X Title: node-api: use fast properties in node_api_create_object_with_properties by colinhacks · Pull Request #66470 · nodejs/node

Description: Description Objects created with node_api_create_object_with_properties() are in dictionary mode, because the call uses v8::Object::New(). Their properties are about 7x slower to read than an object literal's, and about 70x slower with a NULL prototype, where each object also gets a map of its own. This change keeps a cache of v8::DictionaryTemplate per env, keyed by a hash of the property names. Core already creates objects from dictionary templates in cares_wrap.cc and other places. A list of names passed once is only recorded by its hash. When the same list comes back, a template is created for it. Later objects with those names are instances of the template, with fast properties and one shared map. The first 256 lists that come back keep their template for the life of the env. Later lists keep using v8::Object::New(). Symbols, strings that are not one-byte, array-index names, duplicate names and lists of more than 127 names also keep using v8::Object::New(), because a template cannot hold them. A prototype other than Object.prototype costs one SetPrototype() per object, as in NewDictionaryInstanceNullProto(). Fixes #66441 Benchmark Measured with benchmark/compare.js, 30 runs per binary, both built from adcd028 on an Apple M1 Max (macOS 26.6) that was also running other work. The benchmark uses 20 properties and a NULL prototype. Every row below has p < 0.001 (Welch's t-test). operation n before (ops/s) after (ops/s) after / before create 100 906,183 788,484 0.87 create 1,000 826,700 1,128,979 1.37 create 10,000 1,234,144 950,498 0.77 create 100,000 1,338,166 699,711 0.52 create 1,000,000 529,317 400,732 0.76 read 100 1,427,576 2,501,004 1.75 read 1,000 3,420,600 11,972,203 3.50 read 10,000 5,376,966 19,301,626 3.59 read 100,000 6,765,430 57,977,854 8.57 read 1,000,000 6,834,671 73,790,321 10.80 The rows with method='old' (napi_create_object and napi_set_property) do not use the changed code. They moved by -1% to +7%. Creation with a NULL prototype is slower because of the SetPrototype() call. With Object.prototype it is unchanged. The reproduction from #66441 measures both, with 10 properties and 100,000 objects, in ns per property (median of 3 runs; an object literal reads at 0.78 ns): prototype read before read after create before create after Object.prototype 5.67 0.72 38.4 39.3 NULL 53.08 0.84 41.6 62.2 Validation python3 tools/test.py --mode=release js-native-api node-api benchmark/test-benchmark-napi out/Release/cctest --gtest_filter='*NodeApi*:*Napi*' make lint-cpp, git-clang-format, and ESLint on the changed JS files The new test fails on the unpatched build at the first fast-properties check. It passed 300 runs in a row on the patched build. AI disclosure: I used a coding agent for the investigation, patch, benchmarks, and PR text. It checked the template and Object::New() behavior against the V8 source, built Node.js, and ran the tests above. I approved the PR and will handle review comments myself.

Open Graph Description: Description Objects created with node_api_create_object_with_properties() are in dictionary mode, because the call uses v8::Object::New(). Their properties are about 7x slower to read than an objec...

X Description: Description Objects created with node_api_create_object_with_properties() are in dictionary mode, because the call uses v8::Object::New(). Their properties are about 7x slower to read than an objec...

Opengraph URL: https://github.com/nodejs/node/pull/66470

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