--- title: Read-Copy-Update (RCU): The Secret to Lock-Free Performance description: Read-Copy-Update (RCU) is a concurrency pattern that eliminates lock overhead from the read path, delivering 10-30x better read performance than traditional... canonical: https://daily.dev/posts/read-copy-update-rcu-the-secret-to-lock-free-performance-ekig5oxyy twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Read-Copy-Update (RCU): The Secret to Lock-Free Performance | daily.dev og:description: Read-Copy-Update (RCU) is a concurrency pattern that eliminates lock overhead from the read path, delivering 10-30x better read performance than traditional... og:url: https://daily.dev/posts/read-copy-update-rcu-the-secret-to-lock-free-performance-ekig5oxyy og:image: https://api.daily.dev/og/posts/ekIg5oXyY.png og:image:alt: Read-Copy-Update (RCU): The Secret to Lock-Free Performance 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. # Read-Copy-Update (RCU): The Secret to Lock-Free Performance **[InfoQ](https://daily.dev/sources/infoq)** · 26 min read · 0 upvotes · 0 comments ## Summary Read-Copy-Update (RCU) is a concurrency pattern that eliminates lock overhead from the read path, delivering 10-30x better read performance than traditional reader-writer locks. The pattern works in three phases: readers access data lock-free via pointer dereference, writers create a modified copy and atomically swap the pointer, then defer memory reclamation until a grace period confirms all pre-update readers have finished. Benchmarks show a 110% improvement over pthread rwlock at 1000:1 read-to-write ratios. Production systems including Linux kernel networking, PostgreSQL MVCC, Kubernetes/etcd, and Envoy proxy all use RCU principles. The key trade-off is eventual consistency — readers may briefly see stale data. RCU is appropriate when read-to-write ratios exceed 10:1 and brief inconsistency is tolerable. Common pitfalls include using pointers outside critical sections (causing use-after-free bugs) and blocking inside critical sections (preventing grace period completion). C++26 standardizes RCU via P2545R4, and production libraries include liburcu for C/C++ and crossbeam-epoch for Rust. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Read Locks Are Not Your Friends](https://daily.dev/posts/read-locks-are-not-your-friends-rfms5918e) · Lobsters · 0 upvotes · 0 comments --- Tags: [#performance](https://daily.dev/tags/performance), [#linux](https://daily.dev/tags/linux) [View this post on daily.dev](https://daily.dev/posts/read-copy-update-rcu-the-secret-to-lock-free-performance-ekig5oxyy) ```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":"Read-Copy-Update (RCU): The Secret to Lock-Free Performance","url":"https://daily.dev/posts/read-copy-update-rcu-the-secret-to-lock-free-performance-ekig5oxyy","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/read-copy-update-rcu-the-secret-to-lock-free-performance-ekig5oxyy"},"datePublished":"2026-03-06T09:01:52.730Z","dateModified":"2026-03-06T09:02:22.250Z","description":"Read-Copy-Update (RCU) is a concurrency pattern that eliminates lock overhead from the read path, delivering 10-30x better read performance than traditional...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/27cb89a65f2a34c7c20f2c0c4f30cd04?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/27cb89a65f2a34c7c20f2c0c4f30cd04?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"InfoQ","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":"InfoQ","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/afc3bced3e1e4b188dd9127017a60e0c","url":"https://daily.dev/sources/infoq"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/read-copy-update-rcu-the-secret-to-lock-free-performance-ekig5oxyy","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"performance,linux","timeRequired":"PT26M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"InfoQ","item":"https://daily.dev/sources/infoq"},{"@type":"ListItem","position":3,"name":"Read-Copy-Update (RCU): The Secret to Lock-Free Performance"}]} ```