jest: [Bug]: the jest tests performance dropped badly from node 14 to 19

So, jest has a huge community, but nobody is interested in performance?!?

Just want to note that the fix from Node 21 made it into Node 20.10.0. My unit test runtime dropped by 50% with this fix.

Same thing. A huge drop of performance. I’ve used Angular 12 with jest 26 and CI and node 16 and tests run 5 minutes. Now I’m using Angular 15 with jest 29 and Node 18 and I’m getting 10-11 minutes with the same pack of tests.

Hi, same here. Any solution?

🎉

I recently got a new dev machine and wanted to re-run jest + webpack on versions 14/16/18 of nodejs.

new machine specs: System: OS: Windows 10 10.0.19044 CPU: (16) x64 11th Gen Intel® Core™ i9-11950H @ 2.60GHz Binaries: Node: 14.18.1 - C:\Program Files\nodejs\node.EXE Yarn: 1.22.19 - C:\Program Files (x86)\Yarn\bin\yarn.CMD npm: 6.14.15 - C:\Program Files\nodejs\npm.CMD

Below are the updated results:

Note: none of the source code or npm packages were changed between runs. On cold runs, I did delete cached webpack artefacts.

From node 14 to 18, our jest tests ran 27% slower while our webpack build was 18% faster. This leads me to believe that the issue is not solely with node itself but some interaction between node + jest.

Let me know if there is any other information that you need.

Do you have a reproduction for this somehow?

And can you try with Node 21, that should have some good improvements (but not related to regression between 18 and 20)

This is a duplicate of #11956 follow that incident for updates - tldr light is at the end of the tunnel - there is a pr that fixed node js

jest 29.5.1, node 16.10 -> 18.16

at github actions runner with maxWorkers=2

16.10 18.16 21min 27min

Ours went from 3min to 9min with 5 shards : /

Node 16

Node 20

Tested with node 18, same thing. Same workflow on both.

I’m currently in the process of upgrading a project to node 18 and jest 29 and noticed a similar drop in performance on newer node versions.

Our specs: Test Files: 495 Tests: 4135

jest config:

module.exports = {
    testEnvironment: "jsdom",
    testEnvironmentOptions: {
        url: "http://localhost" 
    },
    setupFiles: ["core-js", "<rootDir>/tests/setup"],
    setupFilesAfterEnv: [
        "<rootDir>/tests/matchers.ts",
        "<rootDir>/tests/jsdomPatch.js",
        "<rootDir>/enzyme.config.js"
    ],
    testMatch: ["**/*.spec.(js|ts|jsx|tsx)"],
    moduleFileExtensions: ["js", "json", "ts", "jsx", "tsx"],
    moduleNameMapper: require("./aliases.config").jest,
    coverageDirectory: "<rootDir>/coverage",
    coverageReporters: ["html", "json", "cobertura"],
    reporters: [
        "default"
    ],
    transformIgnorePatterns: [
        "node_modules/(?!(react-grid-layout/css|react-resizable/css|lodash-es|nanoid)/)"
    ],
    testResultsProcessor: "jest-sonar-reporter"
};

Environment System: OS: Windows 10 10.0.19044 CPU: (8) x64 Intel® Core™ i7-7700K CPU @ 4.20GHz Binaries: Node: 14.18.1 - C:\Program Files\nodejs\node.EXE Yarn: 1.22.17 - C:\Program Files\nodejs\yarn.CMD npm: 6.14.8 - ~\AppData\Roaming\npm\npm.CMD npmPackages: jest: 29.4.3 => 29.4.3

Test Performance Note: only node version was changed when collecting these run times. Cold runs always started with jest --clearCache running prior to the tests themselves

node 14.18.1 cold run: 239s hot run: 196s

node 18.14.2 cold run: 276s hot run: 240s