The tar archive format, its extensions, and why GNU tar extracts in quadratic time - Mort's Ramblings
Date: 2022-07-23 Git: https://gitlab.com/mort96/blog/blob/published/content/00000-home/00014-tar.md (If you're here from Google and just need help with tar being slow: If you trust the tar archive, extract with -P to make tar fast.) A couple of days ago, I had a 518GiB tar.gz file (1.1 TiB uncompressed) that I had to extract. At first, GNU tar was doing a great job, chewing through the tar.gz at a
Ask HN: What are some cool but obscure data structures you know about? | Hacker News
I'm very interested in what types of interesting data structures are out there HN. Totally your preference.I'll start: bloom filters. Lets you test if a value is definitely NOT in a list of pre-stored values (or POSSIBLY in a list - with adjustable probability that influences storage of the values.) Good use-case: routing. Say you have a list of 1 million IPs that are black listed. A trivial algor
A DNS name compression algorithm – Tony Finch
In our previous episode, I optimized tolower() using SWAR tricks. That was in fact a side-quest to a side-quest to a side-quest. The first side-quest was trying out a new DNS name compression algorithm; in BIND, compression is performance-critical and a heavy user of tolower(), which is what set me off on the second and third side-quests. Now let’s pop the stack, and talk about DNS names. names on
リアルタイム共同編集のアルゴリズム (Operational Transformation; OT) を理解する試み – RORO
Google Docsのように文書を複数人でリアルタイムに共同編集できるアプリケーションがあります。あのような機能は、多かれ少なかれ、Operational Transformation (OT; 操作変換) という考え方を使って実現されているようです。興味があったので、このOTについて調べてみました。 (追記: これからは OT でなく CRDT だという話 → I was wrong. CRDTs are the future) なおGoogle Docsではいわゆる「リッチテキスト」を共同編集できますが、ここでは話を簡単にするために「プレーンテキスト」を共同編集することを想定します。 リアルタイム共同編集の流れ 共同編集システムの登場人物は次の通りです： サーバ x 1（各クライアントから届く編集操作をもとに、最新の文書を保持します） クライアント x N（文書を編集する側です） そ
GitHub - mxgmn/MarkovJunior: Probabilistic language based on pattern matching and constraint propagation, 153 examples
MarkovJunior is a probabilistic programming language where programs are combinations of rewrite rules and inference is performed via constraint propagation. MarkovJunior is named after mathematician Andrey Andreyevich Markov, who defined and studied what is now called Markov algorithms. In its basic form, a MarkovJunior program is an ordered list of rewrite rules. For example, MazeBacktracker (ani
Vectorized and performance-portable Quicksort
The latest news from Google on open source releases, major projects, events, and outreach programs for early career developers. Today we're sharing open source code that can sort arrays of numbers about ten times as fast as the C++ std::sort, and outperforms state of the art architecture-specific algorithms, while being portable across all modern CPU architectures. Below we discuss how we achieved
共同編集を支える技術とライブラリの活用 - ICS MEDIA
『Google Docs』や『Figma』といったリアルタイムな共同編集ツールの恩恵を受けている人は数多くいるでしょう。『Visual Studio Live Share』のようなエンジニアに嬉しいツールも生まれ、今日ではオンライン上でも円滑なコミュニケーションが可能になっています。 これらのツールの基礎にあるのが「共同編集」のテクノロジーです。本記事ではこの技術に焦点を当て、その仕組みと主にフロントエンドでの実用例について紹介します。 記事の前半では、リアルタイムな共同編集に用いられる技術やアルゴリズムについて、発展の歴史とあわせて紹介します。解説用のコードにはJavaScriptおよびTypeScriptを使用しますが、フロントエンドエンジニアに限らず共同編集の仕組みについて気になる読者が知識を深めるきっかけとなるはずです。 さらに後半ではフロントエンドの開発者目線で、前半で紹介した技
Use Fast Data Algorithms | Joey Lynch's Site
Disclaimer: There are lies, damn lies, and benchmarks from some random person on the internet. If you are considering taking some of the advice in this post please remember to test your specific workloads, which might have different bottlenecks. Also the implementation quality in your particular software stack for your particular hardware matters a lot. For this post I’ll be playing with a ~5 GiB
Changing std::sort at Google’s Scale and Beyond
TL;DR; We are changing std::sort in LLVM’s libcxx. That’s a long story of what it took us to get there and all possible consequences, bugs you might encounter with examples from open source. We provide some benchmarks, perspective, why we did this in the first place and what it cost us with exciting ideas from Hyrum’s Law to reinforcement learning. All changes went into open source and thus I can
リリース、障害情報などのサービスのお知らせ
最新の人気エントリーの配信
j次のブックマーク
k前のブックマーク
lあとで読む
eコメント一覧を開く
oページを開く
The many flavors of hashing
sqlglot/posts/sql_diff.md at main · tobymao/sqlglot
Closing the B-tree vs. LSM-tree Write Amplification Gap on Modern Storage Hardware with Built-in Transparent Compression
素数の数え上げと乗法的関数の和
GitHub - Bodigrim/text-rope: A wrapper around Text for fast line/column navigation and logarithmic concatenation
Determining the intersection point of two lists in O(1) space
Fast Matrix Multiplication (Animated)
notes/fast-case-conversion at master · apankrat/notes
Luhn algorithm using SWAR and SIMD
So Long Surrogates: How we moved to UTF-8 in Haskell
GitHub - scandum/crumsort: A branchless unstable quicksort / mergesort that is highly adaptive.