Improving DataView performance in V8 · V8
Show navigation DataViews are one of the two possible ways to do low-level memory accesses in JavaScript, the other one being TypedArrays. Up until now, DataViews were much less optimized than TypedArrays in V8, resulting in lower performance on tasks such as graphics-intensive workloads or when decoding/encoding binary data. The reasons for this have been mostly historical choices, like the fact
Celebrating 10 years of V8 · V8
Show navigation This month marks the 10-year anniversary of shipping not just Google Chrome, but also the V8 project. This post gives an overview of major milestones for the V8 project in the past 10 years as well as the years before, when the project was still secret. A visualization of the V8 code base over time, created using gource.Before V8 shipped: the early years #Google hired Lars Bak in t
Embedded builtins · V8
V8 built-in functions (builtins) consume memory in every instance of V8. The builtin count, average size, and the number of V8 instances per Chrome browser tab have been growing significantly. This blog post describes how we reduced the median V8 heap size per website by 19% over the past year. Background #V8 ships with an extensive library of JavaScript (JS) built-in functions. Many builtins are
V8 release v6.9 · V8
Every six weeks, we create a new branch of V8 as part of our release process. Each version is branched from V8’s Git master immediately before a Chrome Beta milestone. Today we’re pleased to announce our newest branch, V8 version 6.9, which is in beta until its release in coordination with Chrome 69 Stable in several weeks. V8 v6.9 is filled with all sorts of developer-facing goodies. This post pr
V8 release v6.8 · V8
Every six weeks, we create a new branch of V8 as part of our release process. Each version is branched from V8’s Git master immediately before a Chrome Beta milestone. Today we’re pleased to announce our newest branch, V8 version 6.8, which is in beta until its release in coordination with Chrome 68 Stable in several weeks. V8 v6.8 is filled with all sorts of developer-facing goodies. This post pr
Concurrent marking in V8 · V8
Show navigation This post describes the garbage collection technique called concurrent marking. The optimization allows a JavaScript application to continue execution while the garbage collector scans the heap to find and mark live objects. Our benchmarks show that concurrent marking reduces the time spent marking on the main thread by 60%–70%. Concurrent marking is the last puzzle piece of the Or
Adding BigInts to V8 · V8
Over the past couple of months, we have implemented support for BigInts in V8, as currently specified by this proposal, to be included in a future version of ECMAScript. The following post tells the story of our adventures. TL;DR #As a JavaScript programmer, you now[1] have integers with arbitrary[2] precision in your toolbox: const a = 2172141653n; const b = 15346349309n; a * b; // → 333344445555
V8 release v6.7 · V8
Every six weeks, we create a new branch of V8 as part of our release process. Each version is branched from V8’s Git master immediately before a Chrome Beta milestone. Today we’re pleased to announce our newest branch, V8 version 6.7, which is in beta until its release in coordination with Chrome 67 Stable in several weeks. V8 v6.7 is filled with all sorts of developer-facing goodies. This post pr
Improved code caching · V8
V8 uses code caching to cache the generated code for frequently-used scripts. Starting with Chrome 66, we are caching more code by generating the cache after top-level execution. This leads to a 20–40% reduction in parse and compilation time during the initial load. Background #V8 uses two kinds of code caching to cache generated code to be reused later. The first is the in-memory cache that is av
Background compilation · V8
TL;DR: Starting with Chrome 66, V8 compiles JavaScript source code on a background thread, reducing the amount of time spent compiling on the main thread by between 5% to 20% on typical websites. Background #Since version 41, Chrome has supported parsing of JavaScript source files on a background thread via V8’s StreamedSource API. This enables V8 to start parsing JavaScript source code as soon as
katagaitai CTF勉強会 #11 Pwnable編 - PlaidCTF 2016 Pwnable666 js_sandbox / katagaitai CTF #11
katagaitai CTF勉強会 #11 関東|med，#10+11 関西|medで発表した資料です． 閲覧自由ですが，社会人の方はなるべくWikipediaなどお好きなサービスやOSSに￥1000の寄付をしてあげて下さい(←流行らせたい)． Chromeなどで使われるJavaScriptエンジンであるV8のPwnable問です．JavaScriptエンジンに対する最近のexploitの多くで利用される，length系exploitの初歩を解説しています．攻撃テクニックが中心だった過去資料とはことなり，V8の構造についての解説が多めです．問題バイナリのDLリンクはこちらです．→https://goo.gl/73vQ1U
Lazy deserialization · V8
Show navigation TL;DR: Lazy deserialization was recently enabled by default in V8 v6.4, reducing V8’s memory consumption by over 500 KB per browser tab on average. Read on to find out more! Introducing V8 snapshots #But first, let’s take a step back and have a look at how V8 uses heap snapshots to speed up creation of new Isolates (which roughly correspond to a browser tab in Chrome). My colleague
V8 release v6.5 · V8
Every six weeks, we create a new branch of V8 as part of our release process. Each version is branched from V8’s Git master immediately before a Chrome Beta milestone. Today we’re pleased to announce our newest branch, V8 version 6.5, which is in beta until its release in coordination with Chrome 65 Stable in several weeks. V8 v6.5 is filled with all sorts of developer-facing goodies. This post pr
V8 memory quiz
V8 is the JavaScript engine that Chrome and Node use to run JavaScript code. Take this quiz to discover some interesting implementation details about how V8 stores values in memory. Reading this probably won’t help you fix any performance issues you encounter day-to-day. 1. How much memory is used per array element? (Divide total program memory by array length) var a = [] // You'll see why we're u
Optimizing hash tables: hiding the hash code · V8
Show navigation ECMAScript 2015 introduced several new data structures such as Map, Set, WeakSet, and WeakMap, all of which use hash tables under the hood. This post details the recent improvements in how V8 v6.3+ stores the keys in hash tables. Hash code #A hash function is used to map a given key to a location in the hash table. A hash code is the result of running this hash function over a give
Chrome welcomes Speedometer 2.0! · V8
Show navigation Ever since its initial release of Speedometer 1.0 in 2014, the Blink and V8 teams have been using the benchmark as a proxy for real-world use of popular JavaScript frameworks and we achieved considerable speedups on this benchmark. We verified independently that these improvements translate to real user benefits by measuring against real-world websites and observed that improvement
V8の Object.entries/values を高速化した - abcdefGets
V8のObject.entries/valuesを高速化したよというお話 Object.entires/values そもそもObject.entries、Object.valuesとは何かというと、 GitHub - tc39/proposal-object-values-entries: ECMAScript Proposal, specs, and reference implementation for Object.values/Object.entriesで提案されていた仕様である。 見事stage4まで到達して採用された。 仕様 機能をおさらいしておく Object.entries(O) const ret = Object.entries({a: 1, b: 2, c: 3}); console.log(ret) // [['a', 1], ['b', 2], ['c',
V8 javascript engineについての細かい話 (Node.js Advent Calendar 2017) - abcdefGets
Node.js Advent Calendar 2017 25日目の記事です。トリとなります。 さて先日11/26・27日に行われたNode学園祭でv8について発表させて頂いたが、 30分という制約上色々カットせざるを得なかった。 またv8のコードを読む・コントリビュートする上で伝えられる事も色々と溜まったので一度アウトプットすることにした。 というわけでまとまりのない記事になる可能性が高いがご容赦いただけると助かります。 事前資料 以下のスライドがNode学園祭の発表資料なので読んどいていただけると理解がはやいかも speakerdeck.com 前準備 チェックアウト v8はGitHubに直接はホスティングされていない。 GitHub上にあるv8リポジトリはミラーで実際にはchromium.googlesource.comにホスティングされている。 ただし開発の際にはGitHubのリポ
V8 release v6.4 · V8
Every six weeks, we create a new branch of V8 as part of our release process. Each version is branched from V8’s Git master immediately before a Chrome Beta milestone. Today we’re pleased to announce our newest branch, V8 version 6.4, which is in beta until its release in coordination with Chrome 64 Stable in several weeks. V8 v6.4 is filled with all sorts of developer-facing goodies. This post pr
JavaScript code coverage · V8
Show navigation Code coverage provides information about whether, and optionally how often certain parts of an application have been executed. It’s commonly used to determine how thoroughly a test suite exercises a particular codebase. Why is it useful? #As a JavaScript developer, you may often find yourself in a situation in which code coverage could be useful. For instance: Interested in the qua
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