Profiling WebAssembly with pprof and wzprof

10th September 2024

Agenda

• What is Go?
• Profiling with pprof
• What is WebAssembly?
• Profiling WebAssembly with wzprof
• CPU and Memory profiling with wzprof
• Generate profilers using wzprof
• Visualize the memory profile
• Visualize the cpu profile
• Future of profiling WebAssembly with wzprof

Speaker - Rajiv Ranjan Singh

twitter.com/therajiv

• Software Engineer at A.P. Moller - Maersk
• Graduated in 2022 from JSS Academy of Technical Education, Bengaluru, India
• Google Summer of Code 2024, 2023, and 2022 LFX Mentorship 2021, and Google Season of Docs 2021, and 2020
• Previously worked with Lummo, redBus, and Economize

What is Go?

• Multi-paradigm programming language
• Memory-safe with automated memory management
• Portable, compiles to a multitude of platforms
• The go program is the entrypoint to the Go toolchain
• It standardizes how developers build and maintain their applications
• Provides tooling for building, profiling, testing, and managing dependencies

Profiling with pprof

• Performance profiling tool
• pprof is a tool for visualization and analysis of profiling data
• Package pprof serves via its HTTP server runtime profiling data in the format expected by the pprof visualization tool
• Can be used to profile CPU, memory, block profiling, and goroutine profiling
• WebAssembly eases cross-language profiling

What is WebAssembly?

• WebAssembly is a binary instruction format
• Compact byte code as compilation target
• Virtual machines do compilation at run time
• Host functions for external communication
• wasmimport and wasmexport for function calls

Profiling WebAssembly with wzprof

• Cross-language CPU and memory profiler for WebAssembly
• Based on Wazero and the pprof data format
• Exposes profiles on pprof http endpoints
• Compatible with continuous-profiler systems supporting pprof profiles
• Instruments all wasm function calls and captures the stack trace for all of them

CPU and Memory profiling with wzprof

• CPU profiling
• Memory profiling

Generate profilers using wzprof

• Write the code

package main

import "fmt"

func main() {
    fmt.Println("Hello wzprof!")
}

• Build Go code to WebAssembly

GOOS=wasip1 GOARCH=wasm go build -o main.wasm main.go

• Create the memory, and CPU profiles

wzprof -sample 1 -memprofile /Users/rajiv.singh/Desktop/hello-wasm/memprofile.out ./main.wasm
wzprof -sample 1 -cpuprofile /Users/rajiv.singh/Desktop/hello-wasm/cpuprofile.out ./main.wasm

Visualize the memory profile

go tool pprof -http :4001 memprofile.out

Visualize the cpu profile

go tool pprof -http :6002 cpuprofile.out

Future of profiling WebAssembly with wzprof

• Profiling from the guest, through host functions, down to the kernel syscalls
• eBPF cross paths with WebAssembly
• Profiling interpreted language runtimes

Thank you