--- title: Parallel Nix evaluation | daily.dev description: Determinate Systems has implemented a parallel evaluator for Nix, addressing the long-standing single-threaded limitation that causes slow evaluation of large... canonical: https://daily.dev/posts/parallel-nix-evaluation-aycxygss4 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Parallel Nix evaluation | daily.dev og:description: Determinate Systems has implemented a parallel evaluator for Nix, addressing the long-standing single-threaded limitation that causes slow evaluation of large... og:url: https://daily.dev/posts/parallel-nix-evaluation-aycxygss4 og:image: https://api.daily.dev/og/posts/aYcxYgss4.png og:image:alt: Parallel Nix evaluation og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Parallel Nix evaluation **[Determinate Systems](https://daily.dev/sources/determinate-systems)** · 7 min read · 0 upvotes · 0 comments ## Summary Determinate Systems has implemented a parallel evaluator for Nix, addressing the long-standing single-threaded limitation that causes slow evaluation of large Nixpkgs and NixOS configurations. The post explains how Nix's lazy evaluation via thunks was made thread-safe using atomic compare-and-swap operations and three new value states (Pending, Awaited, Failed), without adding per-value mutexes. Benchmarks on a 12-core Ryzen 5900X show 3-4x speedups: nix flake show dropped from 23.7s to 5.77s, and nix search nixpkgs from 11.82s to 3.88s. The implementation is available as a draft PR and can be tested via a provided Nix command, with more subcommands planned for parallelization. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Building \(systems\) software with Nix](https://daily.dev/posts/building-systems-software-with-nix-jbw3o8thj) · Lobsters · 1 upvotes · 0 comments - [Changelog: faster evaluation and FedRAMP cache keys](https://daily.dev/posts/changelog-faster-evaluation-and-fedramp-cache-keys-qbkpwjrox) · Determinate Systems · 0 upvotes · 0 comments - [One flake to rule them all](https://daily.dev/posts/one-flake-to-rule-them-all-oyz5p8fiz) · Farid Zakaria’s Blog · 1 upvotes · 1 comments - [The Great Nix Flake Check](https://daily.dev/posts/the-great-nix-flake-check-joelq4xlg) · Lobsters · 0 upvotes · 0 comments --- Tags: [#performance](https://daily.dev/tags/performance) [View this post on daily.dev](https://daily.dev/posts/parallel-nix-evaluation-aycxygss4) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Parallel Nix evaluation","url":"https://daily.dev/posts/parallel-nix-evaluation-aycxygss4","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/parallel-nix-evaluation-aycxygss4"},"datePublished":"2026-07-26T07:48:39.979Z","dateModified":"2026-07-26T07:53:01.721Z","description":"Determinate Systems has implemented a parallel evaluator for Nix, addressing the long-standing single-threaded limitation that causes slow evaluation of large...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/6f3be26bdd0e492b50a047388cb0bc67?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/6f3be26bdd0e492b50a047388cb0bc67?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Determinate Systems","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Determinate Systems","logo":"https://media.daily.dev/image/upload/s--E2qrkc9w--/c_limit,w_256/f_auto,q_auto/v1785052094/logos/determinate-systems?_a=BAMAMicg0","url":"https://daily.dev/sources/determinate-systems"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/parallel-nix-evaluation-aycxygss4","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"performance","timeRequired":"PT7M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Determinate Systems","item":"https://daily.dev/sources/determinate-systems"},{"@type":"ListItem","position":3,"name":"Parallel Nix evaluation"}]} ```