Overview¶

Package pprof serves via its HTTP server runtime profiling datain the format expected by the pprof visualization tool.

The package is typically only imported for the side effect ofregistering its HTTP handlers.The handled paths all begin with /debug/pprof/.As of Go 1.22, all the paths must be requested with GET.

To use pprof, link this package into your program:

import _ "net/http/pprof"

If your application is not already running an http server, youneed to start one. Add "net/http" and "log" to your imports andthe following code to your main function:

go func() {log.Println(http.ListenAndServe("localhost:6060", nil))}()

By default, all the profiles listed inruntime/pprof.Profile areavailable (viaHandler), in addition to theCmdline,Profile,Symbol,andTrace profiles defined in this package.If you are not using DefaultServeMux, you will have to register handlerswith the mux you are using.

Parameters¶

Parameters can be passed via GET query params:

• debug=N (all profiles): response format: N = 0: binary (default), N > 0: plaintext
• gc=N (heap profile): N > 0: run a garbage collection cycle before profiling
• seconds=N (allocs, block, goroutine, heap, mutex, threadcreate profiles): return a delta profile
• seconds=N (cpu (profile), trace profiles): profile for the given duration

Usage examples¶

Use the pprof tool to look at the heap profile:

go tool pprof http://localhost:6060/debug/pprof/heap

Or to look at a 30-second CPU profile:

go tool pprof http://localhost:6060/debug/pprof/profile?seconds=30

Or to look at the goroutine blocking profile, after callingruntime.SetBlockProfileRate in your program:

go tool pprof http://localhost:6060/debug/pprof/block

Or to look at the holders of contended mutexes, after callingruntime.SetMutexProfileFraction in your program:

go tool pprof http://localhost:6060/debug/pprof/mutex

The package also exports a handler that serves execution trace datafor the "go tool trace" command. To collect a 5-second execution trace:

curl -o trace.out http://localhost:6060/debug/pprof/trace?seconds=5go tool trace trace.out

To view all available profiles, openhttp://localhost:6060/debug/pprof/in your browser.

For a study of the facility in action, visithttps://blog.golang.org/2011/06/profiling-go-programs.html.

Index¶

• func Cmdline(w http.ResponseWriter, r *http.Request)
• func Handler(name string) http.Handler
• func Index(w http.ResponseWriter, r *http.Request)
• func Profile(w http.ResponseWriter, r *http.Request)
• func Symbol(w http.ResponseWriter, r *http.Request)
• func Trace(w http.ResponseWriter, r *http.Request)

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