https://zengjinji.github.io/Recent content on zengjinji · Technical NotesHugoen-USFri, 06 Nov 2026 15:10:53 +0800https://zengjinji.github.io/posts/luajit-arm64-infinite-loop/Fri, 06 Nov 2026 15:10:53 +0800https://zengjinji.github.io/posts/luajit-arm64-infinite-loop/<blockquote> <p>A three-year production investigation: from 100% CPU usage and loops that would never terminate to discovering that LuaJIT&rsquo;s ARM64 code generator had dropped an instruction that should have been executed.</p> </blockquote> <p>Our gateway runs on OpenResty, with most of its business logic written in Lua. OpenResty uses LuaJIT underneath. In JIT mode, LuaJIT compiles Lua code into machine instructions that the CPU can execute directly to improve performance. In everyday development, we usually focus on whether the Lua logic is correct. This time, however, the problem was in <strong>the machine code generated by the JIT compiler</strong>.</p> <h2 id="1-symptoms-in-production">1. Symptoms in production</h2> <p>Our production fleet originally consisted entirely of x86 machines, and everything worked normally. After introducing ARM machines, we began encountering a series of LuaJIT-related problems on those machines.</p>https://zengjinji.github.io/about/Mon, 01 Jan 0001 00:00:00 +0000https://zengjinji.github.io/about/<p>Hello, I&rsquo;m <strong>zengjinji</strong>. Welcome to my personal blog.</p> <p>This is where I keep notes on engineering, reading, and everyday learning. I hope each post helps me—and anyone facing a similar problem—find a clearer path the next time around.</p> <h2 id="what-youll-find-here">What you&rsquo;ll find here</h2> <ul> <li><strong>Engineering practice</strong>: implementation notes, troubleshooting, and the reasoning behind a solution.</li> <li><strong>Learning notes</strong>: working through new ideas in my own words.</li> <li><strong>Everyday observations</strong>: thoughts worth keeping and revisiting.</li> </ul> <h2 id="about-the-site">About the site</h2> <p>The blog is built with <a href="https://gohugo.io/">Hugo</a> and published on <a href="https://pages.github.com/">GitHub Pages</a>. Posts are stored as Markdown, and the pages do not depend on external fonts or scripts.</p> <p>English is the default language. Use the language button next to About to switch between English and Chinese, including the translated version of the article you&rsquo;re reading.</p>