Lesson 2: CGo Performance and Pitfalls — The hidden cost of crossing the boundary

Thu, 24 Oct 2024 00:00:00 +0000

When I profiled a service that was spending 40% of its time in cgo calls, I thought I was measuring the C library. I was not. I was measuring the overhead of getting to the C library. The actual C work was fast. What was slow was the goroutine-to-OS-thread transition, the stack switching, and the runtime bookkeeping that happens every single time Go code crosses the C boundary. Understanding this overhead is what separates cgo code that runs fine from cgo code that becomes a bottleneck.

Lesson 1: CGo Basics — When you need C and how to call it safely

Mon, 22 Jul 2024 00:00:00 +0000

There is a saying in the Go community: “cgo is not Go.” It is not an insult. It is a warning. The moment you add import "C" to a file, you are no longer writing a pure Go program — you are writing a Go program that manages a C boundary, and all the things that make Go comfortable (fast builds, easy cross-compilation, the race detector, straightforward stack traces) become harder. You are doing it on purpose, because the alternative is worse.

CGo on

Lesson 2: CGo Performance and Pitfalls — The hidden cost of crossing the boundary

Lesson 1: CGo Basics — When you need C and how to call it safely