Ashok Menon
e6d5f2e80d
Summary: blairv recently brought an issue with heap snapshots to our attention: When captured from iOS, the viewer would quite regularly hang forever instead of capturing the snapshot. Further investigation showed that it was because the message that Hermes sends to indicate that it had finished sending chunks of the heap snapshot was arriving to chrome before the last chunk of the snapshot. This caused Chrome to believe the snapshot was malformed. I confirmed that: - Sends from the Hermes Inspector were occurring in the correct order. - The WebSocket protocol, being built on top of TCP, also preserves order. - The Inspector Proxy in Metro was preserving the order of requests it was given, but the responses were already in the wrong order when they reached it. This left the code that Hermes' Inspector calls into to send its messages. On iOS, the logic to send the request is run on the global dispatch queue which can and does schedule jobs concurrently with each other. Because the messages containing heap snapshot chunks are much larger than the "Ok" message used to indicate the end of the snapshot, the earlier chunk message would often lose the race with the later "Ok" message. There was already a serial background queue used by the websocket server to schedule the actual sending of the message. I re-use it in this diff to process the message as well. The architecture of the [same code in Android](https://our.intern.facebook.com/intern/diffusion/FBS/browse/master/xplat/js/react-native-github/ReactAndroid/src/main/java/com/facebook/react/devsupport/InspectorPackagerConnection.java?commit=64c8954ec7be555509437db6944b9a71a350e87c&lines=283) initially seems to be broken in the same way, but it is not, because AsyncTask does not run tasks concurrently any more because Google found it exposed too many concurrency bugs to do so. pakoito, it seems like you might be somewhat familiar with what's going on here. Let me know if what I've done is sensible. Reviewed By: pakoito Differential Revision: D17106960 fbshipit-source-id: af85ff1753324340bb55fc63048e8bd424c8a983
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 own 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 9.0 and Android 4.1 (API 16) 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 repo, @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 the React Native Community, @react-native-community/react-native-releases.
👏 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 bugfixes 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.