Nginx C Module Debug

When your nginx module crashes in production and you're staring at a cryptic segfault, this is your systematic debugging guide. It covers 45 rules across core dump analysis, memory bug detection with AddressSanitizer and Valgrind, GDB workflow for inspecting request state, and tracing request flow through nginx's phase handlers and filter chains. The priority ranking helps you start with crash signatures and NULL pointer patterns before diving into dynamic tracing tools. It's built from nginx.org's official development docs and complements the nginx-c-modules skill by focusing purely on diagnosis rather than correct implementation. Most useful when you need to debug use-after-free bugs, pool corruption, or subrequest crashes that only happen under load.