Joyee Cheung
@JoyeeCheung
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She/Her. My brain is full of food, plants, museums, languages, and code fragments from V8 & Node.js.
Joined August 2012
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Landed experimental support for synchronous require(esm) to load ES modules without top-level await 🥳
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Also, I wrote a bit about my understanding on why this took ~5 years more than it should have :
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Woke up to an accepted
@v8js
committer nomination today 😊 Thank you to everyone who have helped me along the way!
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Just landed a new flag in Node.js - e.g
node --heapsnapshot-near-heap-limit=3
to take up to 3 snapshots when the heap is on the edge of OOM so you can compare and see what objects are allocated before the Node.js instance crashes due to OOM
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Landed a PR to enable ccache-like env var for caching Node.js module compilation.
Numbers from folks trying an earlier version of this:
tsc --version: ~90ms -> ~40ms
yarn --version: ~165ms -> ~115ms
npm run echo (bundled by ncc): ~150ms -> ~110ms
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If you are stuck on 16 because of the 100x perf regression/memory leak of vm.Script compilation (or just Jest users getting stuck on 16 due to perf reasons/memory leak), the fix/workaround is in 20 now (v18 backport is WIP)
New Node.js v20.10.0 'Iron' (LTS) release up now ⚡💚
Details here:
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Today is my last day at Alibaba. It has been an amazing experience working with some of the best Node.js developers in China. 🙏
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New blog posts (a series again because it became too long and should be split for readability again 🤪): Memory leak regression testing with V8/Node.js, part 1 - memory usage-based testing
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No more confusing "native modules" in Node.js: from now on built-in JS modules in Node.js are called "built-in modules" and the the dynamically-linked shared objects loaded into the Node.js prcesses are called "addons":
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Working on my
@NodeConfEU
talk and I start to question if I can really squeeze all these into 25 minutes 🥹....✂️✂️✂️
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Just landed the PR that implements run-time startup snapshots as an experimental feature in Node.js 🎉 Should be available in a Node.js v18 semver-minor release soon.
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Managed to get the TypeScript compiler up and running with the Node.js user land snapshot prototype
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Just landed it as a build-time feature (i.e. embedding a bundled app into the binary if you compile Node.js from source). Looking into making it a run-time feature (i.e. generating/loading app snapshots from disk with the official Node.js binary)
Managed to get the TypeScript compiler up and running with the Node.js user land snapshot prototype
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The Node.js collaboration summit seemed to work out pretty well. Trying to write a document/blog post about what I learned co-organizing it. It was great working on this with
@littledan
@matteocollina
@TChetwin
et al, and thanks
@TechAtBloomberg
for the amazing support!
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So happy to see the first bug report of require(esm) after the v22 release that I started fixing it in the train station and opened a PR on the train 🥹 The more battle-tested it is, the quicker it can graduate to stable!
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I will be giving a talk at
#NodeCongress
about Node.js startup snapshots. Can't wait to see some friendly faces that I haven't seen for a long time in Berlin! 🥰
@NodeCongress
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New blog post: How does Node.js load its built-in/native modules?
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For my own research into "why is the ESM loader creating so many promises", I implemented a local --trace-promises flag and..it creates 65 promises to load empty.mjs 🫣 (maybe this should be upstreamed as an internal flag to help paying attention to this in core)
@ThePrimeagen
@stephenbelanger
To make this easy, I made this promise counting library! This checks how many promises are created between two points in code.
You can even isolate to an async continuation to filter out noise, or get the callsites of created promises!
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The first version of the JS API of llnode (as a normal Node.js addon) just landed!
Thanks to the the reviewers in each iteration and
@rnchamberlain
for the original work, also h/t to the N-API team: it got much simpler after being rewritten with N-API!
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I actually managed to write a blog post about Node core development before 2018 ends!
(new year resolution: write more blog posts)
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Landed a new crypto.hash() API in Node.js for one-shot hashing, for small (<5MB) and readily available data it can be 1.2-2x faster than using crypto.createHash() (for bigger inputs, streaming via crypto.createHash() is still preferred).
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What do you think about adding a CLI flag to Node.js that profiles the application during the length of its lifetime and writes the CPU profile to disk before it exits? (similar to --prof, but backed by the better-supported v8 CPU profiler)
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I wrote some notes about how the uncaught exception handling is implemented in Node.js:
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Just landed an experimental V8 startup snapshot JS API in Node.js for specifying (de/)serialization callbacks as well as main functions for the deserialized app 🎉 (only available for build-time snapshots for now, runtime snapshot is WIP)
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Slides for my talk about Web APIs in Node.js core
@jsconfeu
Thanks
@littledan
@jasnell
@MylesBorins
for helping me improve the talk (as well as work on spec & implementations that I've mentioned in the talk)!
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I've been asked about this quite a few times lately, so in case you want to know how to become a
@nodejs
core collaborator (who has commit access to the nodejs/node GitHub repo and CI access for PRs), this is where the process is documented:
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Landed a PR on Node.js master to share the code cache of builtin modules & bootstrappers compiled among the main thread & worker threads so launching workers can be ~2x faster than launching child processes (thanks
@addaleax
for the review!)
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Me: I am going to Tokyo next month
My sister: that's not the kind of life that I imagine a programmer will have
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Landed a new v8.queryObjects() API similar to the one in Chrome DevTools’ console, which allows searching for objects with a matching prototype on its prototype chain. Useful for testing against memory leaks (what it was used for internally in Node.js)
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I am going to give a talk about how to contribute to Node.js core at the code-and-learn event in Beijing this month. What do you think I should cover in my talk? I am trying to be technical and practical in the talk, with topics like
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Another day, another home-grown Node.js internal simplified with a new JS feature
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Slides for my talk about the bootstrap of Node.js core at the OpenJS collaboration summit:
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Slides for my talk "JavaScript and C++ in Node.js core - How do they talk to each other?"
@NodeConfEU
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I am going to give a talk at
#NodeJSInteractive
tomorrow on post-mortem diagnostics in JS - or, how we teach lldb to understand the v8 object model - and the JS API of llnode. Check it out if you are at the conference and are also interested in debuggers!
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I was reminded again why I didn't go to local tech meetups anymore yesterday. There will always be guys making a big deal out of a female programmer being anywhere near competent. Then there will be questions about if she's single. It's sad but it's a prevalent thing here.
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Just moved the stability index of Node.js single executable applications from "Experimental: This feature is being designed and will change" to "Active development" as the design is less likely to change now (still many feature requests left tho)
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I implemented the automatic leak detection algorithm used by Eclipse's MAT on V8 heap snapshots as a Node.js CLI. See the test/fixtures directory for common types of leaks that it can help to identify
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这周日我会去在浙大玉泉举办的 Node 地下铁做一个关于 Node.js 启动的分享。 I am going to give a talk about Node.js bootstrap at Node subway hosted at the Yuquan Campus of Zhejiang University this Sunday.
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Apart from optimizations and features, there are long-standing bugs in Node.js like & that affected many users but didn't get enough dedications to fix due to complexity. I am grateful that Bloomberg allowed me to work on them ❤️
Bloomberg invests in Node.js Core. Shouldn't you?
In this blog post, I wrote about our sponsorship of:
-
@JoyeeCheung
as a Node TSC member
-
@AndreuBotella
working on AsyncContext, supporting observability
-
@NicoloRibaudo
accelerating modules with `import defer`
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Weekend nerd-sniping ends with "oh it's GC underperforming in a microbenchmark that allocates in a tight loop...again" & "oh it's JS string -> embedder buffer conversions being slow...again"
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Special release of node-core-utils, @ v1.13.0: a tool that automatically grabs test failures and their reasons from their CI and display it (+ write a pastable markdown to your clipboard!)
Demo:
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Slides for our (me &
@caio_nepo
) talk "Implementing one feature set in two JavaScript engines"
@webhackfest
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New blog post: Things I learned from organizing a hybrid unconference - hopefully it helps other event organizing beginners like me!
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Was excited to see many new faces at the OpenJS collaboration summit and the regular Node.js crowd :3
Many thanks to the organizers
@ladyleet
@evahowe
@jorydotcom
@keywordnew
@matteocollina
et al!
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Anyone wants to join a session about fixing Node.js core's almost-never-green-CI on Sep 18? 😜
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Arriving in London ahead of the Node.js collaboration summit 🛬
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Just landed a PR in Node.js that allows DevTools to display detached embedder objects in the heap snapshots differently - with the script below, the Node / Blob object is detached (only held alive by JS) initially, then attached (held alive by C++) after URL.createObjectURL()
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Tips: you can use to easily download/update and install the latest d8 binaries so there is no need to compile it from source!
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Tried not to look at GitHub this weekend and failed catastrophically…well at least I did manage to stare at some things that are unrelated to computers.
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Oh wow the C++ wrappers of N-API are much easier to use than NAN/the V8 API. Kudos to everyone who worked on the initiative!
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@jasnell
@codebycruz
@littledan
@jarredsumner
@yagiznizipli
If anything, unhealthy discussions on social media would only make people like me who are mostly blocked by social barriers less motivated to improve ESM in Node.js, not more
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From a recent conversation I realize that Node.js user land snapshot could be useful even without support for loading other user modules (because there are bundlers), so maybe it would be nice to have an experimental prototype landed first while working on further support..🤔
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llnode @ v1.7.0
- Detailed output with `v8 findjsobjects -d`
- Fix `v8 bt` with v8 6.4 (still broken on 6.5+)
- Build file refactors, might fix some bugs on some Linux distros and FreeBSD
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Me after writing ~250 lines of tests: I don't expect this to just pass at the first attempt, let me compile it and run it with the debugger
...but it passed o.O
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Support for Bigint in node fs Stats objects just landed on master!
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If you are a member of the
@nodejs
organization (including collaborators, WG/team members) considering going to Vancouver for JS Interactive/collab summit this October, please participate in this survey so we can plan ahead for the cost & space needed!
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Writing a slow but effective tool for finding out the correct order to backport Node.js PRs with the least amount of conflicts possible...
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I wrote a handwavy explanation about how the fixes in Node.js v21.1.0 lowered memory usage and run time of Jest tests (maybe in other frameworks compiling scripts the same way too) - in case I never manage to finish a less handwavy blog post about them..😂
hmm so that was still wrong, and reverted a while ago, and then while I was working on something else related to memory, this came up to me … so giving it a try again..
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Apparently I looked gloomy when sinking into my thoughts on a plane, even the flight attendant asked “are you okay? You look so sad”…
Good news is I got the ticket to a museum I have wanted to visit for a long time so I got better things to stare at for the weekend 🤓
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As someone who submitted her first PR to Node.js (and first PR to a big open source project) at a code-and-learn event and have been sticking around for ~2 years and counting, I want to thank everyone who have contributed to this mission :)
I always enjoy code and learn. Even if most of these folks never contribute to node.js again, for many this is their first time contributing to any open source. The excitement when that pr is opened is beautiful to see.
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I am making a CLI alternative to node-reivew. Browesr extentions are friendly but can't really use for automation🤔
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As someone who have never contributed to a large OSS project/used English as working language before getting involved in Node.js, I've learned a great deal from
@trott
(and others) about communication and empathy 😊
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Managed to finish a few blog posts before 2023 ends! Part 1: analysis of the memory leaks and use-after-frees and the attempted & reverted fix
I naively thought about writing a blog post after the fixes are landed and released, but then an endless thread of adjacent long-standing bugs just keep coming in 🥹
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Some interesting finding from my little adventure into crypto.createHash() performance (these are based on microbenchmarks that hash 10-100K buffer/strings of 10-100 bytes in a tight loop so validity of the numbers vary considering impact of GC) 🧵
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New tricks necessary for debugging v8 with lldb recently:
To map the source:
(lldb) settings set target.source-map "../../" "/path/to/v8/dir"
Somehow v8::internal::Object is now ambiguous, so:
(lldb) p _v8_internal_Print_Object(*((void**)(v8_local.val_)))
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@jasnell
@codebycruz
@littledan
@jarredsumner
@yagiznizipli
I have talked about why I dared to work on ESM now, but not before here. There are things inspired by Bun in Node.js, but require(esm) isn’t one of those. The group who worked on ESM in Node.js before mostly consist of different people.
@naugtur
@ScriptedAlchemy
I think it would still happen without me. ESM spec was already made conditionally synchronous in 2019 thanks to bundlers making case for that semantics. It just needs sb who knows this and dares to work on the energy-draining Node.js ESM loader and knows a bit about V8 to do it…
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This supports both CJS and ESM. More background in , this is part of a larger effort to finally sunset CJS module loader monkey patching (which the npm package v8-compile-cache does, and also why it doesn't support ESM or import())
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I did a talk at the OpenJS collaboration summit last month about some of the details of this work and future work (snapshotting as much bootstrap as possible is still WIP):
I'm thrilled to see this sophisticated work from
@JoyeeCheung
on improving Node startup time with V8 snapshots finally shipping.
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Now that
@mhdawson1
(who’s been tweeting about the talks at
@NodeConfEU
) is on stage himself, here is a pic of him talking about how to build native addons like it’s 2023 and a bit of history of the evolution of addon development
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@rough__sea
Theoretically it would’ve been preventable if other maintainers/reviewers noticed that the code was suspicious. AFAICT the problem happened in a project with very few maintainers and there was pressure to add the attacker as maintainer.
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@robpalmer2
@_rafaelgss
I confirm that with Node.js master (v8 9.8) the performance cliff between class fields and traditional properties is gone - private symbols are still slower since there's no type feedback for them, but they are unstable APIs that users should not rely on anyway.
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Remote participation of the collaborator meeting at NodeConf () wasn’t set up, though it wasn’t any kind of decision making meeting, some interesting discussions happened, so here's my recap for folks who were not able to be there 🧵
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Removing 3 global object interceptor calls from vm.createContext() (one with the help of snapshot), makes it 12% faster - I knew that interceptor calls are slow but I didn't expect them to be that slow. 🧐 If you are using vm contexts, be sure to cache access to the globals.
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node-core-utils @ v1.12.0
- new `git node v8` command to maintain `deps/v8` (h/t to
@targos89
)
- suggest -x and --autosquash for git rebase
- misc fixes
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A really long-overdue node-core-utils release..v1.14.0:
- Various fixes and improvements to ncu-ci
- Better state handling in git-node land
Please update if you use the npm release!
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The Node.js collaborators in China are going to organize a Node.js Code + Learn on the second day of COSCon, Nov. 2-3 in Shanghai!
坐标在中国的 Node.js Collaborators 们打算在 11 月 2-3 日上海的 COSCon 第二天组织一个 Node.js Code + Learn！ 🥰
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I am surprised that I have not seen much mention about the recent package-maintenance () effort led by
@mhdawson1
today in my TL.. background: People are aware and there's tons of work open to everybody who wants to help!
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Nearly forgot this: I gave a presentation on the status of llnode during the Node.js diagnostics summit. here are the slides in case there are users who want to know what's going on there
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Picking up CI gardening Friday again and trying to fix...8 (?) flakes and isolating 1 flake ($%@$! to go, can't count, don't want to count 🥺)
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@NicoloRibaudo
(Still need to wait a bit until this is no longer under —experimental-require-module, so please try it and report any bugs to help making that happen!)
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IDK why but I always thought that Node.js links to v8_monolithic, until I read the gyp files and realized that it doesn't (it links to a bunch of other libs that v8_monolithic consists of).
Then I realized that I already knew this >1 year ago and wrote about it in a doc🤦♀️
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