The Adventurer’s Guide to Forking the Go Runtime
summary
Creates a reproducible set of rolling patches applied to Go 1.20.7 that inject tracing into the runtime by adding a Trace field to the G struct and hooking goexit/gostart (goxat0/newproc1), plus small overlays for HTTP and database/sql. Uses go:linkname and unsafe to implement hooks outside the runtime, emits OpenTelemetry spans and sends to Jaeger, and traces outbound requests via Traceparent headers. Demo shows per-request tracing without app changes and expands a trace from ~6 spans to 27 spans, revealing DNS/TCP and driver internals.
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chapters (19)
- 0:00Start
- 0:35WHAT'S OUR GOAL?
- 1:16FORKS
- 1:58SETTING UP OUR FORK
- 3:44CREATING OUR BUILD SCRIPT
- 4:29OUR FIRST PATCH
- 5:14A SIMPLE APP
- 5:40SOME GO INTERNALS
- 7:28RUNTIME/PROC.GO
- 9:04DEMO APPLICATION
- 10:56WHAT EXACTLY ARE WE GOING TO DO?
- 13:03GETTING OUR CODE COMPILING AGAIN
- 15:49TRACING REQUESTS
- 16:52PATCHING IT IN
- 19:08TRACEPARENT
- 20:12DESIGNING A SIMPLE SPAN API
- 21:19LET'S START RECORDING SPANS
- 22:50PATCH THE BASE QUERY FUNCTION
- 28:25WHAT ABOUT OTHER APPROACHES?
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