[0.57.0] Metro in React Native 0.57.0 slower than older ?

[Winglonelion]

Maybe it is not a bug. But it happen clarify after my Project upgraded to RN 0.57.0. And i think it need some confirm from community to ensure what happen.

• [yes] Review the documentation: https://facebook.github.io/react-native
• [yes] Search for existing issues: https://github.com/facebook/react-native/issues
• [yes] Use the latest React Native release: https://github.com/facebook/react-native/releases

Environment

Run react-native info in your terminal and paste its contents here.

    System:
      OS: macOS Sierra 10.12.6
      CPU: x64 Intel(R) Xeon(R) CPU E3-1231 v3 @ 3.40GHz
      Memory: 24.88 MB / 16.00 GB
      Shell: 3.2.57 - /bin/bash
    Binaries:
      Node: 8.10.0 - ~/.nvm/versions/node/v8.10.0/bin/node
      Yarn: 1.9.4 - ~/.nvm/versions/node/v8.10.0/bin/yarn
      npm: 6.4.1 - ~/.nvm/versions/node/v8.10.0/bin/npm
      Watchman: 4.7.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 11.2, macOS 10.13, tvOS 11.2, watchOS 4.2
    IDEs:
      Android Studio: 3.1 AI-173.4720617
      Xcode: 9.2/9C40b - /usr/bin/xcodebuild
    npmPackages:
      react: 16.4.0 => 16.5.0 
      react-native: 0.56.0 => 0.57.0 
    npmGlobalPackages:
      react-native-cli: 2.0.1
      react-native-git-upgrade: 0.2.7

Description

The Problems: As above, after upgraded my Project to RN 0.57.0 with babel 7.0.0. When debugging, my Metro server bundling progress spent x10 time to resolve same files and assets than 0.56.0. (30s -> 5 - 7 mins)

It made a large death time in my developing. Anyone met same issues ?

Release build worked fine. It just a problem with Metro Server.

Additional: Because RN devtool and debug server not compatable with RN 0.57.0, so i removed it from dev dependencies. You can see more here: #21054

Reproducible Demo.

I'm not sure. But it happen with this dependencies and configs:

packages.json:

  "dependencies": {
    "react-native": "0.57.0",
    "react": "16.5.0",
}
"devDependencies": {
    "@babel/cli": "7.0.0",
    "@babel/core": "7.0.0",
    "@babel/plugin-proposal-decorators": "7.0.0",
    "@babel/preset-flow": "7.0.0",
    "babel-core": "7.0.0-bridge.0",
    "babel-eslint": "9.0.0-beta.2",
    "babel-jest": "23.6.0",
    "babel-plugin-module-resolver": "3.1.1",
    "babel-plugin-transform-remove-console": "6.9.4",
    "enzyme": "3.6.0",
    "eslint": "5.1.0",
    "eslint-config-airbnb": "17.1.0",
    "eslint-import-resolver-babel-module": "5.0.0-beta.1",
    "eslint-plugin-import": "2.14.0",
    "eslint-plugin-jsx-a11y": "6.1.1",
    "eslint-plugin-react": "7.11.0",
    "eslint-plugin-react-native": "3.3.0",
    "flow-bin": "0.78.0",
    "jest": "23.6.0",
    "jest-util": "23.4.0",
    "metro-react-native-babel-preset": "0.45.2",
    "prettier-eslint": "8.8.2",
    "react-dom": "16.5.0",
    "react-test-renderer": "16.5.0",
    "redux-devtools-extension": "2.13.5",
    "redux-mock-store": "1.5.3",
    "remote-redux-devtools": "0.5.13"
  },

.babelrc:

{
    "presets": [
        "@babel/preset-flow",
        "module:metro-react-native-babel-preset"
    ],
    "env": {
        "production": {
            "plugins": [
                "transform-remove-console"
            ]
        }
    },
    "plugins": [
        [
            "@babel/plugin-proposal-decorators",
            {
                "legacy": true
            }
        ],
        [
            "module-resolver",
            {
                "cwd": "babelrc",
                "alias": {
                    "@js": "./js",
                    "@images": "./images",
                    "underscore": "lodash"
                },
                "extensions": [
                    ".android.js",
                    ".ios.js",
                    ".js"
                ]
            }
        ]
    ],
    "retainLines": true
}

[react-native-bot]

Can you run react-native info and edit your issue to include these results under the Environment section?

If you believe this information is irrelevant to the reported issue, you may write [skip envinfo] under Environment to let us know.

[Winglonelion]

@react-native-bot i added it (Environment). I think you need to smarter :)

[mjmasn]

@Winglonelion I guess it just looks for the React Native Environment Info header, you didn't copy the full output...

But yep, metro seems much slower (like 5x - 10x slower for first build) since upgrading.

  React Native Environment Info:
    System:
      OS: Linux 4.15 Ubuntu 16.04.5 LTS (Xenial Xerus)
      CPU: x64 Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz
      Memory: 1.43 GB / 15.54 GB
      Shell: 4.3.48 - /bin/bash
    Binaries:
      Node: 8.11.0 - ~/.nvm/versions/node/v8.11.0/bin/node
      Yarn: 1.9.4 - /usr/bin/yarn
      npm: 5.6.0 - ~/.nvm/versions/node/v8.11.0/bin/npm
      Watchman: 4.9.0 - /usr/local/bin/watchman
    SDKs:
      Android SDK:
        Build Tools: 23.0.1, 26.0.1, 26.0.2, 26.0.3, 27.0.0, 27.0.3
        API Levels: 16, 19, 22, 23, 26, 27, 28
    IDEs:
      Android Studio: 3.1 AI-173.4907809
    npmPackages:
      react: ^16.5.0 => 16.5.1 
      react-native: 0.57.0 => 0.57.0 
    npmGlobalPackages:
      create-react-native-app: 1.0.0
      react-native-cli: 2.0.1
      react-native-git-upgrade: 0.2.7

[kelset]

This is not a react-native issue, so I don't see why we should keep this open.

If you think that something in Metro is now slower I recommend you open a dedicated issue on that project repo.