Upgrade to Pro — share decks privately, control downloads, hide ads and more …

๐Ÿ‡ฎ๐Ÿ‡ณ React India 2022

๐Ÿ‡ฎ๐Ÿ‡ณ React Indiaย 2022

โ„น๏ธ Deep diving on Concurrent React

Writing fluid user interfaces become more and more challenging as the application complexity increases. In this talk, weโ€™ll explore how proper scheduling improves your appโ€™s experience by diving into some concurrent React features, understanding their rationales, and how they work under the hood.

Matheus Albuquerque

September 23, 2022
Tweet

More Decks by Matheus Albuquerque

Other Decks in Technology

Transcript

  1. ร… Iโ€™M MATHEUS ๐Ÿ™‹ โ† @YTHECOMBINATOR ON THE WEB โ†

    SR. SOFTWARE ENGINEER @MEDALLIA โ† MENTOR @TECHLABS
  2. #1 REACT SOURCE CODE IS CONSTANTLY CHANGING, AND SOME THOUGHTS

    ARE SPECULATIVE DEEP DIVING ON CONCURRENT REACT
  3. DATA-DRIVEN UI LIBS DOM RECONCILIATION E.G. ANGULAR, POLYMER, LIT-HTML VIRTUAL

    DOM E.G. REACT, VUE, INFERNO REACTIVE E.G. KNOCKOUT, SVELTE, SOLID
  4. DOM RECONCILIATION E.G. ANGULAR, POLYMER, LIT-HTML VIRTUAL DOM E.G. REACT,

    VUE, INFERNO REACTIVE E.G. KNOCKOUT, SVELTE, SOLID DATA-DRIVEN UI LIBS
  5. #QUOTE ๐Ÿ’ฌ โ€œ[โ€ฆ] With React you can build applications without

    even thinking about performance and the default state is fast.โ€ โ€”โ€‰Rethinking Best Practices by Pete Hunt, 2013
  6. โ† GENERATE A VIRTUAL TREE AND THEN DIFF AGAINST THE

    PREVIOUS ITERATION โ† PATCH THE DOM UPDATES โ† USE IMMUTABILITY AND REFERENTIAL EQUALITY TO OPTIMIZE THE PROCESS WHICH RESULTS IN SIGNIFICANT CLONING AND MEMORY ALLOCATION VIRTUAL DOM
  7. #PROTIP ๐Ÿ’ก React doesnโ€™t have any understanding of the values

    running through your app. Itโ€™s not reactive.
  8. VIRTUAL DOM โ† IT HAS BEEN OPTIMIZED WELL ENOUGH IN

    MOST SCENARIOS โ† WE DONโ€™T COMPLAIN ABOUT PERF IN INFERNO OR BUNDLE SIZE IN PREACT โ† THERE ARE LIBRARIES THAT CAN PRODUCE EQUIVALENT/SMALLER BUNDLES (E.G. HyperApp)
  9. VIRTUAL DOM โ† IT'S JUST ONE OF THE APPROACHES WE

    HAVE AND IT'S NEVER A TRUE/FALSE QUESTION โ† UNDERSTANDING ITS KEY TAKEAWAYS HELPS US UNDERSTAND WHERE CONCURRENT REACT FITS
  10. PERFOMANCE PERCEIVED LOAD SPEED HOW QUICKLY A PAGE CAN LOAD

    AND RENDER ALL OF ITS VISUAL ELEMENTS TO THE SCREEN SMOOTHNESS DO TRANSITIONS & ANIMATIONS RENDER AT A CONSISTENT FRAME RATE AND FLOW FLUIDLY? LOAD RESPONSIVENESS HOW QUICKLY A PAGE CAN LOAD/RUN ANY REQUIRED JS IN ORDER FOR COMPONENTS TO RESPOND TO USER INTERACTION RUNTIME RESPONSIVENESS AFTER THE PAGE LOAD, HOW QUICKLY CAN THE PAGE RESPOND TO USER INTERACTION?
  11. PERFOMANCE PERCEIVED LOAD SPEED HOW QUICKLY A PAGE CAN LOAD

    AND RENDER ALL OF ITS VISUAL ELEMENTS TO THE SCREEN LOAD RESPONSIVENESS HOW QUICKLY A PAGE CAN LOAD/RUN ANY REQUIRED JS IN ORDER FOR COMPONENTS TO RESPOND TO USER INTERACTION RUNTIME RESPONSIVENESS AFTER THE PAGE LOAD, HOW QUICKLY CAN THE PAGE RESPOND TO USER INTERACTION? SMOOTHNESS DO TRANSITIONS & ANIMATIONS RENDER AT A CONSISTENT FRAME RATE AND FLOW FLUIDLY?
  12. PHONE USERS EXPERIENCE SLOW FIRST INPUT DELAY ON 7X MORE

    WEBSITES. โ€”โ€‰Web Almanac By HTTP Archive, 2021
  13. DESKTOP PHONE 0 25 50 75 100 SLOW ( >

    = 250MS) AVERAGE FAST (<50 MS) FIRST INPUT DELAY
  14. BUSINESS OUTCOMES โ† LONG TASKS DELAYED TTI โ† AS FIRST-PAGE

    LONG TASK TIME INCREASED, OVERALL CONVERSION RATES DECREASED โ† MOBILE HAD UP TO หœ12X LONGER LONG TASKS โ† OLDER DEVICES COULD BE SPENDING HALF OF THEIR LOAD-TIME ON LONG TASKS โ€”โ€‰AKAMAI AND CHROME RESEARCH, 2017
  15. #QUESTION ๐Ÿค” If you were to summarize Concurrent React in

    one word/expression, whatโ€™d be your pick?
  16. #QUESTION ๐Ÿค” If you were to summarize Concurrent React in

    one word/expression, whatโ€™d be your pick? e.g. fibers โ† units of work Concurrent React โ† ???
  17. DEEP DIVING ON CONCURRENT REACT If you were to summarize

    Concurrent React in one word/expression, whatโ€™d be your pick?
  18. DEEP DIVING ON CONCURRENT REACT If you were to summarize

    Concurrent React in one word/expression, whatโ€™d be your pick? 1st/2nd/3rd ANSWERS โ† REACT BRUSSELS DISCOUNT CODE ๐Ÿ‡ง๐Ÿ‡ช OTHERS โ† STICKERS ๐Ÿ’…
  19. TASKS JAVASCRIPT STYLES LAYOUT PAINT COMPOSITE A UNIT OF WORK

    THAT THE BROWSER DOES TO RENDER A FRAME
  20. LONG TASKS โ† IF A TASK TAKES MORE THAN 50

    MS, USER INPUT FEELS DELAYED โ† BASED ON THE USER-CENTRIC PERFORMANCE MODEL CALLED RAIL โ† THEY TAKE TOO LONG AND BLOCK OTHER TASKS
  21. PARALLELISM โ† MULTIPLE THREADS = MULTIPLE TASKS AT THE SAME

    TIME ON SEPARATE CPU CORES CONCURRENCY โ† SINGLE THREAD + QUICKLY SWITCHING BETWEEN TASKS SCHEDULING โ† CONCURRENCY + TASK PRIORITIZATION TASK RUNNING STRATEGIES
  22. WORKERS โ† VERY DIFFERENT FROM THE THREADS IN C++, JAVA,

    ETC. โ† NO ACCESS TO ANY VARIABLES/CODE FROM THE PAGE THAT CREATED THEM OR VICE VERSA โ† DATA EXCHANGE IS THROUGH MESSAGE-PASSING
  23. WORKERS โ† NO ACCESS TO THE DOM, MAKING UI UPDATES

    FROM A WORKER BARELY IMPOSSIBLE โ† APPS THAT INTEND TO USE THEM HAVE TO ADAPT THEIR ARCHITECTURE TO ACCOMMODATE THESE REQUIREMENTS โ† TWO MODELS: ACTORS & SHARED MEMORY ๐Ÿคฏ
  24. ACTORS โ† EACH ACTOR MAY OR MAY NOT RUN ON

    A SEPARATE THREAD โ† EACH ACTOR FULLY OWNS THE DATA IT IS OPERATING ON โ† ACTORS CAN ONLY SEND/REACT TO MESSAGES โ† MAIN THREAD = ACTOR THAT OWNS THE DOM/UI ๐Ÿคฏ
  25. ACTORS โ† EVERY MESSAGE WE SEND NEEDS TO BE COPIED

    โ† BALANCE: MOVING CODE TO A WORKER VS COMMUNICATION OVERHEAD/WORKER BEING BUSY โ† postMessage IS A FIRE-AND-FORGET MESSAGING MECHANISM WITH NO BUILT-IN UNDERSTANDING OF REQUEST AND RESPONSE ๐Ÿคฏ
  26. SHARED MEMORY โ† ONE DEDICATED TYPE: SharedArrayBuffer โ† A LINEAR

    CHUNK OF MEMORY THAT CAN BE MANIPULATED USING TypedArrays OR DataViews โ† IF SENT VIA postMessage, THE OTHER END GETS A HANDLE TO THE EXACT SAME MEMORY CHUNK ๐Ÿคฏ
  27. SHARED MEMORY โ† MOST OF THE APIS ARE BUILT NO

    CONCURRENT ACCESS TO OBJECTS IN MIND โ† YOU BUILD YOUR OWN MUTEXES AND OTHER CONCURRENT DATA STRUCTURES โ† NO DIRECT WAY OF WORKING ON FAMILIAR OBJECTS/ARRAYS; JUST A SERIES OF BYTES ๐Ÿคฏ
  28. WEB ASSEMBLY โ† WORKERS + SharedArrayBuffers TO SUPPORT THE THREADING

    MODEL OF C++ AND OTHERS โ† BEST EXPERIENCE FOR SHARED-MEMORY MODEL โ† FASTER THAN JS WHEN YOU STAY WITHIN WASM, BUT THE MORE YOU HAVE TO CROSS OVER TO JS APIS THE SLOWER IT IS
  29. WEB ASSEMBLY โ† JAVASCRIPT IS OFTEN FASTER AT DOING DOM

    RENDERING โ† HIGH-LEVEL LIBRARIES CAN BE MORE PERFORMANT THAN LOW-LEVEL WASM IMPLEMENTATIONS โ† DOESNโ€™T OFFER LOT OF THE BENEFITS (AND COMFORT) OF JAVASCRIPT
  30. WORKERS โ† GOOD FOR DATA PROCESSING AND CRUNCHING NUMBERS โ†

    HARD TO USE FOR UI-RELATED STUFF โ† HARDER THAN ADJUSTING IT FOR A SCHEDULER
  31. #QUESTION ๐Ÿค” If you were to summarize Concurrent React in

    one word/expression, whatโ€™d be your pick?
  32. DEEP DIVING ON CONCURRENT REACT If you were to summarize

    Concurrent React in one word/expression, whatโ€™d be your pick?
  33. function resourcefulOperation(value: number) { let newValue = String(value); for (let

    i = 0; i < 1000000; i++) { newValue = `${value} + ${i} = ${value + i}`; } return newValue; } function ResourcefulComponent(props: { value: number }) { const { value } = props; const result = resourcefulOperation(value); return <p>{result}</p>; }
  34. function resourcefulOperation(value: number) { let newValue = String(value); for (let

    i = 0; i < 1000000; i++) { newValue = `${value} + ${i} = ${value + i}`; } return newValue; } function ResourcefulComponent(props: { value: number }) { const { value } = props; const result = resourcefulOperation(value); return <p>{result}</p>; }
  35. function* resourcefulOperation(value: number) { let newValue = String(value); while (true)

    { yield; for (let i = 0; i < 1000000; i++) { newValue = `${value} + ${i} = ${value + i}`; } return newValue; } } const initialValue = 0; const scheduler = new Scheduler(resourcefulOperation, initialValue); function ResourcefulComponent(props: { value: number }) { const { value } = props; const result = scheduler.performUnitOfWork(value); return <p>{result}</p>; }
  36. function* resourcefulOperation(value: number) { let newValue = String(value); while (true)

    { yield; for (let i = 0; i < 1000000; i++) { newValue = `${value} + ${i} = ${value + i}`; } return newValue; } } const initialValue = 0; const scheduler = new Scheduler(resourcefulOperation, initialValue); function ResourcefulComponent(props: { value: number }) { const { value } = props; const result = scheduler.performUnitOfWork(value); return <p>{result}</p>; } PROMOTED TO A GENERATOR YIELDING EXECUTION DOING CONCURRENT TASKS
  37. enum SchedulerState { IDLE = "IDLE", PENDING = "PENDING", DONE

    = "DONE", } class Scheduler<T> { state: SchedulerState; result: T; worker: (data: T) = > Generator; iterator: Generator; constructor(worker: (data: T) = > Generator, initialResult: T) { this.state = SchedulerState.IDLE; this.worker = worker; this.result = initialResult; } performUnitOfWork(data: T) { switch (this.state) { case "IDLE": this.state = SchedulerState.PENDING; this.iterator = this.worker(data); throw Promise.resolve(); case "PENDING": const { value, done } = this.iterator.next(); if (done) { this.result = value; this.state = SchedulerState.DONE; return value; } throw Promise.resolve(); case "DONE": this.state = SchedulerState.IDLE; return this.result; } } }
  38. performUnitOfWork(data: T) { switch (this.state) { case "IDLE": this.state =

    SchedulerState.PENDING; this.iterator = this.worker(data); throw Promise.resolve(); case "PENDING": const { value, done } = this.iterator.next(); if (done) { this.result = value; this.state = SchedulerState.DONE; return value; } throw Promise.resolve(); case "DONE": this.state = SchedulerState.IDLE; return this.result; } }
  39. function resourcefulOperation(value: number) { let newValue = String(value); for (let

    i = 0; i < 1000000; i++) { newValue = `${value} + ${i} = ${value + i}`; } return newValue; } function ResourcefulComponent(props: { value: number }) { const { value } = props; const result = resourcefulOperation(value); return <p>{result}</p>; }
  40. function resourcefulOperation(value: number) { let newValue = String(value); for (let

    i = 0; i < 1000000; i++) { newValue = `${value} + ${i} = ${value + i}`; } return newValue; } function ResourcefulComponent(props: { value: number }) { const [_, startTransition] = useTransition(); const [result, setResult] = useState(""); useEffect(() = > { startTransition(() = > { const newResult = resourcefulOperation(props.value); setResult(newResult); }); }, [props.value]); return <p>{result}</p>; }
  41. โ† A COOPERATIVE MULTITASKING MODEL โ† A SINGLE INTERRUPTIBLE RENDERING

    THREAD โ† RENDERING CAN BE INTERLEAVED WITH OTHER MAIN THREAD TASKS AND OTHER REACT RENDERS โ† AN UPDATE CAN HAPPEN IN THE BACKGROUND WITHOUT BLOCKING THE RESPONSE TO NEW INPUT SCHEDULING
  42. โ†“ ORIGINAL RENDER TASK USER INPUT โ†’ โ†‘ HIGHER PRIORITY

    RENDER TASK โ†“ RESUME ORIGINAL RENDER TASK
  43. โ† IT YIELDS EXECUTION IS BACK TO THE MAIN THREAD

    EVERY 5MS โ† IT'S SMALLER THAN A SINGLE FRAME EVEN ON 120FPS, SO IT WON'T BLOCK ANIMATIONS โ† IN PRACTICE, RENDERING IS INTERRUPTIBLE SCHEDULING
  44. PRIORITY TIMEOUT WHEN I m m ediate SYNCHRONOUSLY TASKS THAT

    NEED TO RUN SYNCHRONOUSLY UserBlocking 250MS RESULTS OF A USER INTERACTION (E.G. A BUTTON CLICK) Normal 5S UPDATES THAT DONโ€™T HAVE TO FEEL INSTANTANEOUS Low 10S TASKS THAT CAN BE DEFERRED BUT MUST STILL COMPLETE EVENTUALLY (E.G. AN ANALYTICS NOTIFICATION) Idle NO TIMEOUT TASKS THAT DO NOT HAVE TO RUN AT ALL (E.G. HIDDEN OFFSCREEN CONTENT)
  45. โ† ONE LANE = ONE BIT IN A BITMASK โ†

    ONE UPDATE IN REACT = ONE LANE โ† ONE RENDER IN REACT = ONE OR MORE LANES โ† UPDATES IN THE SAME LANE RENDER IN THE SAME BATCH. DIFFERENT LANES, SEPARATE BATCHES. RENDER LANES ๐Ÿคฏ
  46. โ† 31 LEVELS OF GRANULARITY (= ONE BITMASK) โ† ALLOWS

    TO CHOOSE WHETHER TO RENDER MULTIPLE TRANSITIONS IN A SINGLE BATCH OR RENDER THEM INDEPENDENTLY โ† REDUCES OVERHEAD OF MULTIPLE LAYOUT PASSES, STYLE RECALCULATIONS, AND MULTIPLE PAINTS RENDER LANES ๐Ÿคฏ
  47. DAILY VISITORS (BEFORE) const DailyVisitors = () = > {

    const [data, setData] = useState(initialData); useEffect(() = > { setData(initialData); }, []); const onChange = (newData) = > { setData(newData); }; return ( <Dashboard data={data} initialData={initialData} onChange={onChange} /> ); }; export default DailyVisitors;
  48. DAILY VISITORS (AFTER) const DailyVisitors = () = > {

    const [data, setData] = useState(initialData); const [, startTransition] = useTransition(); useEffect(() = > { setData(initialData); }, []); const onChange = (newData) = > { startTransition(() = > { setData(newData); }); }; return ( <Dashboard data={data} initialData={initialData} onChange={onChange} /> ); }; export default DailyVisitors;
  49. โ† หœ100K + POINTS PLOTTED โ† SUPPORT FOR SEARCHING AND

    FILTERING โ† USED WORKERS + REDUX-SAGA UTILITIES + DEBOUNCING โ† COULD'VE USED TRANSITIONS CASE #1: MAPS
  50. CASE #2: GAME ADMIN โ† THOUSANDS OF REAL-TIME PLAYERS MESSAGING

    โ† SUPPORT FOR SEARCHING AND FILTERING โ† USED VIRTUALIZATION AND MEMOIZATION โ† COULD'VE USED TRANSITIONS
  51. useSyncExternalStore() function useSyncExternalStore<Snapshot>( subscribe: (onStoreChange: () = > void) =

    > () = > void, getSnapshot: () = > Snapshot, getServerSnapshot?: () = > Snapshot ): Snapshot;
  52. useLocation() function Pathname() { const { pathname } = useLocation();

    return <Badge title={pathname} subtitle="pathname" />; } function Hash() { const { hash } = useLocation(); return <Badge title={hash} subtitle="hash" />; }
  53. useLocation() function Pathname() { const { pathname } = useLocation();

    return <Badge title={pathname} subtitle="pathname" />; } function Hash() { const { hash } = useLocation(); return <Badge title={hash} subtitle="hash" />; } OVER-RETURNING HOOK
  54. useHistory() + useSyncExternalStore() function useHistorySelector(selector) { const history = useHistory();

    return useSyncExternalStore(history.listen, () = > selector(history)); } function Pathname() { const pathname = useHistorySelector((history) = > history.location.pathname); return <Badge title={pathname} subtitle="pathname" />; } function Hash() { const hash = useHistorySelector((history) = > history.location.hash); return <Badge title={hash} subtitle="hash" />; }
  55. function useHistorySelector(selector) { const history = useHistory(); return useSyncExternalStore(history.listen, ()

    = > selector(history)); } function Pathname() { const pathname = useHistorySelector((history) = > history.location.pathname); return <Badge title={pathname} subtitle="pathname" />; } function Hash() { const hash = useHistorySelector((history) = > history.location.hash); return <Badge title={hash} subtitle="hash" />; } useHistory() + useSyncExternalStore()
  56. โ† BEFORE, HYDRATION COULD ONLY BEGIN AFTER THE ENTIRE DATA

    WAS FETCHED AND RENDERED โ† USERS COULDNโ€™T INTERACT WITH THE PAGE UNTIL HYDRATION WAS COMPLETE FOR THE WHOLE PAGE โ† PARTS OF YOUR APP THAT LOAD FAST WOULD ALWAYS HAVE TO WAIT FOR THE SLOW ONES HYDRATION
  57. โ† REACT WON'T WAIT FOR THAT COMPONENT TO LOAD TO

    CONTINUE STREAMING HTML FOR THE REST OF THE PAGE โ† WHEN THE HTML BECOMES AVAILABLE ON THE SERVER, IT WILL BE ADDED TO THE SAME STREAM ALONG WITH A SCRIPT TAG AND INSERTED IN THE RIGHT PLACE SELECTIVE HYDRATION
  58. โ† REACT PRIORITIZES HYDRATING THE PARTS THAT THE USER INTERACTED

    WITH BEFORE THE REST โ† COMPONENTS CAN BECOME INTERACTIVE FASTER BY ALLOWING THE BROWSER TO DO OTHER WORK AT THE SAME TIME AS HYDRATION โ† RESULTS IN LOWER FID AND INP SELECTIVE HYDRATION
  59. WE HAVE A FEW SCHEDULING PRIMITIVES: โ† setTimeout โ† requestAnimationFrame

    โ† requestIdleCallback โ† postMessage SCHEDULING ON THE WEB
  60. โ† EVERYONE SHOULD USE THE SAME SCHEDULER โ† HAVING MORE

    THAN ONE SCHEDULER CAUSES RESOURCE FIGHTING โ† INTERLEAVING TASKS WITH BROWSER WORK (RENDERING, GARBAGE COLLECTION) SCHEDULING ON THE WEB
  61. SCHEDULING API โ† A MORE ROBUST SOLUTION FOR SCHEDULING TASKS

    โ† INTEGRATED DIRECTLY INTO THE EVENT LOOP โ† CONTROL AND SCHEDULE PRIORITIZED TASKS IN A UNITED AND FLEXIBLE WAY โ† ALIGNED WITH THE WORK OF THE REACT TEAM AND IN COOPERATION WITH GOOGLE, W3C AND OTHERS
  62. scheduler.postTask() SCHEDULE AND CONTROL PRIORITIZING TASKS. scheduler.wait() YIELD AND RESUME

    AFTER SOME AMOUNT OF TIME OR PERHAPS AFTER AN EVENT HAS OCCURRED. scheduler.yield() BREAK UP LONG TASKS BY YIELDING TO THE BROWSER AND CONTINUING AFTER BEING RESCHEDULED. isInputPending() DETERMINE IF THE CURRENT TASK IS BLOCKING INPUT EVENTS. SCHEDULING API
  63. scheduler.postTask() scheduler.postTask(() = > { console.log('React Brussels'); }, { delay:

    10 }); scheduler.postTask(() = > { console.log('React India'); }); scheduler.postTask(() = > { console.log('React Alicante'); }); / / 'React India' 'React Alicante' 'React Brussels'
  64. scheduler.postTask() const controller = new TaskController({ priority: "user-blocking" }); const

    signal = controller.signal; console.log(signal.priority); / / 'user-blocking' console.log(signal.aborted); / / 'false' scheduler.postTask(doWork, { signal }); controller.setPriority("background"); controller.abort();
  65. isInputPending() while (workQueue.length > 0) { if (navigator.scheduling.isInputPending()) { /

    / Stop doing work to handle any input event break; } let job = workQueue.shift(); job.execute(); }
  66. scheduler.yield() async function doWork() { while (true) { let hasMoreWork

    = doSomeWork(); if (!hasMoreWork) { return; } if (!navigator.scheduling.isInputPending()) { continue; } await scheduler.yield(); } } ๐Ÿคฏ
  67. โ† SCHEDULING IS AN ALTERNATIVE FOR RESPONSIVE USER INTERFACES โ†

    A WEB STANDARDS PROPOSAL THAT BRINGS A UA SCHEDULER TO THE BROWSER IS BEING COOKED โ† WE CAN SOLVE A LOT AT THE FRAMEWORK LEVEL WITH CONCURRENT REACT AND ITS SCHEDULER SCHEDULING (RECAP)
  68. #NOSILVERBULLET ๐Ÿ”ซ Code that yields too often can cause the

    overhead of scheduling tasks to become a negative influence on your appโ€™s overall performance.
  69. โ† DETECTION AND SCHEDULING HAVE AN OVERHEAD โ† NO CORRECT

    CHUNK SIZE THAT FITS ALL DEVICES โ† PARTIALLY COMPLETE INTERFACES CAN INCREASE THE TOTAL COST OF LAYOUT AND PAINT โ† HARD TO FIND THE RIGHT SPOT BETWEEN PERF AND AMOUNT OF BLOCKING SCHEDULING (BAD PARTS) ๐Ÿคฏ
  70. #PROTIP ๐Ÿ’ก Start with observability services or libraries like web-vitals.

    Then create your own abstractions on top of the web + React (e.g. custom hooks).
  71. TIMING USER TIMING ALLOWS YOU TO MARK POINTS IN TIME

    AND THEN MEASURE THE DURATION BETWEEN THOSE MARKS. EVENT TIMING EVENT PROCESSING TIME + TIME UNTIL THE NEXT FRAME CAN BE RENDERED. THE BASIS FOR THE FID METRIC. ELEMENT TIMING MEASURE THE RENDER TIME OF SPECIFIC ELEMENTS. THE BASIS FOR THE LCP METRIC.
  72. PROFILING LONG TASKS API REPORTS TASKS THAT TAKES LONGER THAN

    50 MS AND IT'S THE BASIS FOR TTI AND TBT METRICS JS SELF-PROFILING API PROFILE SPECIFIC COMPLEX OPERATIONS AND IDENTIFY HOT SPOTS USING A SAMPLING PROFILER UserAgentSpecificMemory DETECT MEMORY LEAKS IN APPS THAT HANDLE A HUGE VOLUME OF DATA
  73. { name: "same-origin-descendant", entryType: "longtask", startTime: 1023.40999995591, duration: 187.19000002602115, attribution:

    [ { name: "unknown", entryType: "taskattribution", startTime: 0, duration: 0, containerType: "iframe", containerSrc: "child.html", containerId: "", containerName: "child1" } ] } { bytes: 1000000, breakdown: [ { bytes: 1000000, attribution: [ { url: "https://example.com", scope: "Window", }, ], types: ["JS", "DOM"], }, { bytes: 0, attribution: [], types: [], }, ], } { "frames": [ { "name": "Profiler" }, { "column": 0, "line": 100, "name": "", "resourceId": 0 }, { "name": "set innerHTML" }, { "column": 10, "line": 10, "name": "A", "resourceId": 1 } { "column": 20, "line": 20, "name": "B", "resourceId": 1 } ], "resources": [ "https://example.com/page", "https://example.com/app.js", ], "samples": [ { "stackId": 0, "timestamp": 161.99500000476837 }, { "stackId": 2, "timestamp": 182.43499994277954 }, { "timestamp": 197.43499994277954 }, { "timestamp": 213.32999992370605 }, { "stackId": 3, "timestamp": 228.59999990463257 }, ], "stacks": [ { "frameId": 0 }, { "frameId": 2 }, { "frameId": 3 }, { "frameId": 4, "parentId": 2 } ] } LONG TASKS SELF-PROFILING USERAGENT MEMORY ๐Ÿคฏ
  74. โ† I/O LIBRARIES LIKE react-fetch โ† BUILT-IN <Cache> FOR DATA

    FETCHING LIBRARIES TO INTEGRATE WITH <Suspense> โ† <Suspense> FOR CPU-BOUND TREES TO IMMEDIATELY FALLBACK WITHOUT EVEN TRYING TO RENDER THE FUTURE ๐Ÿคฏ
  75. โ† useInsertionEffect FOR STYLESHEET LIBRARIES โ† THE <Offscreen> COMPONENT โ†

    SERVER COMPONENTS โ† NATIVE SCHEDULING PRIMITIVES ON THE BROWSER โ† AND MUCH MORE! THE FUTURE ๐Ÿคฏ
  76. #1 DEEP DIVING ON CONCURRENT REACT REACT HAS BEEN PUSHING

    WEB APIS TO THE FUTURE E.G. THE SCHEDULER API AND DISCUSSIONS AROUND EFFECT HANDLERS
  77. #2 DEEP DIVING ON CONCURRENT REACT REACT TRIES TO ADDRESS

    THE LACK OF SOME JS/WEB PLATFORM RESOURCES E.G. EFFECT HANDLERS, CONTINUATIONS & THE SCHEDULER API
  78. #3 DEEP DIVING ON CONCURRENT REACT UNDERSTANDING THESE INTERNALS AND

    THEIR RATIONALES HELPS US IMPLEMENT OUR OWN ABSTRACTIONS E.G. THE GENERATOR-BASED SCHEDULER