05-profiling

Profiling Code

We can use the go tooling in conjunction with the Graph Visualization Tools and Ghostscript. These tools will allow us to graph the profiles we create.

Note: Profiling on the Mac is broken. This post talks about how to hack to OS X Kernel to make it work.
http://research.swtch.com/macpprof
https://godoc.org/rsc.io/pprof_mac_fix

Installing Tools

download files

Dave Cheney's Profile Package

go get Dave Cheney's profiling package. He has done a nice job abstracting all the boilerplate code required. If you are interested in understanding how to do this without the profile package, read this (http://saml.rilspace.org/profiling-and-creating-call-graphs-for-go-programs-with-go-tool-pprof)

go get github.com/davecheney/profile

Graph Visualization Tools

Download the package for your target OS/Arch: http://www.graphviz.org/Download.php

Ghostscript

This is not an easy step for Mac users since there is no prebuilt distribution.

Download and uncompress the source code: http://ghostscript.com/download/gsdnld.html

./configure
make
make install

Code Changes

We need to add some changes to main to get the profiling data we need.

import "github.com/davecheney/profile"

// main is the entry point for the application.
func main() {
	cfg := profile.Config{
		MemProfile:     true,
		CPUProfile:     true,
		ProfilePath:    ".",  // store profiles in current directory
		NoShutdownHook: true, // do not hook SIGINT
	}

	// p.Stop() must be called before the program exits to
	// ensure profiling information is written to disk.
	p := profile.Start(&cfg)
	defer p.Stop()

	. . .
}

Running and Creating Profile Graph

go build
./example1
go tool pprof --pdf ./example1 cpu.pprof > callgraph.pdf
go tool pprof --pdf ./example1 mem.pprof > callgraph.pdf

// See all the options
go tool pprof -h

Links

http://golang.org/blog/profiling-go-programs

http://golang.org/pkg/runtime/pprof/

https://golang.org/pkg/net/http/pprof/

https://godoc.org/rsc.io/pprof_mac_fix

Code Review

HTTP Service (Go Playground)

All material is licensed under the Apache License Version 2.0, January 2004.