--- title: OpenAI Fixes 18-Year-Old GNU libunwind Bug by Treating... description: OpenAI engineers discovered two unrelated bugs in Rockset, their C++ data infrastructure powering ChatGPT, by applying 'epidemiological debugging' — building a... canonical: https://daily.dev/posts/openai-fixes-18-year-old-gnu-libunwind-bug-by-treating-crash-debugging-like-epidemiology-laln47lxr twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: OpenAI Fixes 18-Year-Old GNU libunwind Bug by Treating Crash Debugging Like Epidemiology | daily.dev og:description: OpenAI engineers discovered two unrelated bugs in Rockset, their C++ data infrastructure powering ChatGPT, by applying 'epidemiological debugging' — building a... og:url: https://daily.dev/posts/openai-fixes-18-year-old-gnu-libunwind-bug-by-treating-crash-debugging-like-epidemiology-laln47lxr og:image: https://api.daily.dev/og/posts/laLN47Lxr.png og:image:alt: OpenAI Fixes 18-Year-Old GNU libunwind Bug by Treating Crash Debugging Like Epidemiology 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. # OpenAI Fixes 18-Year-Old GNU libunwind Bug by Treating Crash Debugging Like Epidemiology **[InfoQ](https://daily.dev/sources/infoq)** · 4 min read · 0 upvotes · 0 comments ## Summary OpenAI engineers discovered two unrelated bugs in Rockset, their C++ data infrastructure powering ChatGPT, by applying 'epidemiological debugging' — building a pipeline to analyze every production core dump from the past year at a population level rather than inspecting individual crashes. This revealed a silent hardware CPU corruption on a single Azure host and an 18-year-old race condition in GNU libunwind's _Ux86_64_setcontext function. The libunwind bug involves a one-instruction-wide window where the stack pointer is updated before the instruction pointer is read, allowing a signal to corrupt the struct. OpenAI's heavy use of timer-based SIGUSR2 signals made this theoretical race a real production crash. The fix — reordering instructions so %rip is read before %rsp is updated — was upstreamed to GNU libunwind. The key lesson: building complete, labeled population data across all failures reveals structure that individual case analysis cannot. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [How we found a bug in Go's arm64 compiler](https://daily.dev/posts/how-we-found-a-bug-in-go-s-arm64-compiler-igpy1eqbw) · Cloudflare · 48 upvotes · 1 comments - [RocksDB development finds a CPU bug](https://daily.dev/posts/rocksdb-development-finds-a-cpu-bug-ogvqjvlwb) · Lobsters · 0 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/openai-fixes-18-year-old-gnu-libunwind-bug-by-treating-crash-debugging-like-epidemiology-laln47lxr) ```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":"OpenAI Fixes 18-Year-Old GNU libunwind Bug by Treating Crash Debugging Like Epidemiology","url":"https://daily.dev/posts/openai-fixes-18-year-old-gnu-libunwind-bug-by-treating-crash-debugging-like-epidemiology-laln47lxr","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/openai-fixes-18-year-old-gnu-libunwind-bug-by-treating-crash-debugging-like-epidemiology-laln47lxr"},"datePublished":"2026-07-09T10:30:29.650Z","dateModified":"2026-07-09T10:30:49.907Z","description":"OpenAI engineers discovered two unrelated bugs in Rockset, their C++ data infrastructure powering ChatGPT, by applying 'epidemiological debugging' — building a...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/0d72fff7f2d368a10f81d27cae72bcac?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/0d72fff7f2d368a10f81d27cae72bcac?_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/openai-fixes-18-year-old-gnu-libunwind-bug-by-treating-crash-debugging-like-epidemiology-laln47lxr","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"","timeRequired":"PT4M"} {"@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":"OpenAI Fixes 18-Year-Old GNU libunwind Bug by Treating Crash Debugging Like Epidemiology"}]} ```