Marc Rousavy
778382ad3d
Summary: Okay the title is a bit clickbaity, but this is actually true. (on Android) We (Janic, Szymon, Ruby and Me) discovered something interesting. React Native uses `mmap` for mapping the JS bundle to RAM, to avoid having to load the entire thing instantly at app startup. Ruby doubted that this was true - so we investigated. Apparently on Android, resources are **compressed**. And if the JS bundle is stored compressed, it has to be uncompressed before it can be loaded into RAM, hence not allowing it to be mmapp'ed! (see [`_CompressedAsset::getBuffer`](https://cs.android.com/android/platform/superproject/+/master:frameworks/base/libs/androidfw/Asset.cpp;l=903?q=Asset.cpp)) So with this PR, we now add `.bundle` files to `noCompress` in the react-native gradle plugin, which disables compression for the JS bundle. We discovered while improving the performance of one of our clients: **Discord**. In our tests, **this improved the TTI of the Discord app by 400ms!! (or 12%)** 🤯🚀 NOTE: Yes, the .apk will now be bigger. But; Google Play compresses it anyways, so the **download size** of your .apk will likely not increase by much. It will be bigger on disk though. ## Changelog: [ANDROID] [CHANGED] Add option to disable bundle compression to improve startup time <!-- Help reviewers and the release process by writing your own changelog entry. Pick one each for the category and type tags: [ANDROID|GENERAL|IOS|INTERNAL] [BREAKING|ADDED|CHANGED|DEPRECATED|REMOVED|FIXED|SECURITY] - Message For more details, see: https://reactnative.dev/contributing/changelogs-in-pull-requests Pull Request resolved: https://github.com/facebook/react-native/pull/49449 Test Plan: ### 1. Verify compression is disabled Build two apps, one with this patch and one without. When I did this using the RN community template, the one without this patch was 47,6 MB, and the one with this patch was 48 MB in size. So the .apk got bigger, which is what we expected ### 2. Verify app startup is faster Use tools like react-native-performance or custom markers to measure TTI. In our tests, we shaved off 400ms from the startup time, which was about 12% of Discord's total TTI. (on a low-end Android device) In Expensify, we improved the TTI by 14-20% with this change (source: https://github.com/Expensify/App/pull/56930) Reviewed By: javache, cipolleschi Differential Revision: D69742221 Pulled By: cortinico fbshipit-source-id: bd59d77662bd30a3acdbb2e9f8d8f23db922c3f2
React Native
Learn once, write anywhere:
Build mobile apps with React.
Getting Started · Learn the Basics · Showcase · Contribute · Community · Support
React Native brings React's declarative UI framework to iOS and Android. With React Native, you use native UI controls and have full access to the native platform.
- Declarative. React makes it painless to create interactive UIs. Declarative views make your code more predictable and easier to debug.
- Component-Based. Build encapsulated components that manage their state, then compose them to make complex UIs.
- Developer Velocity. See local changes in seconds. Changes to JavaScript code can be live reloaded without rebuilding the native app.
- Portability. Reuse code across iOS, Android, and other platforms.
React Native is developed and supported by many companies and individual core contributors. Find out more in our ecosystem overview.
Contents
- Requirements
- Building your first React Native app
- Documentation
- Upgrading
- How to Contribute
- Code of Conduct
- License
📋 Requirements
React Native apps may target iOS 15.1 and Android 7.0 (API 24) or newer. You may use Windows, macOS, or Linux as your development operating system, though building and running iOS apps is limited to macOS. Tools like Expo can be used to work around this.
🎉 Building your first React Native app
Follow the Getting Started guide. The recommended way to install React Native depends on your project. Here you can find short guides for the most common scenarios:
📖 Documentation
The full documentation for React Native can be found on our website.
The React Native documentation discusses components, APIs, and topics that are specific to React Native. For further documentation on the React API that is shared between React Native and React DOM, refer to the React documentation.
The source for the React Native documentation and website is hosted on a separate repository, @facebook/react-native-website.
🚀 Upgrading
Upgrading to new versions of React Native may give you access to more APIs, views, developer tools, and other goodies. See the Upgrading Guide for instructions.
React Native releases are discussed in this discussion repo.
👏 How to Contribute
The main purpose of this repository is to continue evolving React Native core. We want to make contributing to this project as easy and transparent as possible, and we are grateful to the community for contributing bug fixes and improvements. Read below to learn how you can take part in improving React Native.
Code of Conduct
Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.
Contributing Guide
Read our Contributing Guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to React Native.
Open Source Roadmap
You can learn more about our vision for React Native in the Roadmap.
Good First Issues
We have a list of good first issues that contain bugs which have a relatively limited scope. This is a great place to get started, gain experience, and get familiar with our contribution process.
Discussions
Larger discussions and proposals are discussed in @react-native-community/discussions-and-proposals.
📄 License
React Native is MIT licensed, as found in the LICENSE file.
React Native documentation is Creative Commons licensed, as found in the LICENSE-docs file.