How to connect a profiler in Go? How to take profiles?

In Go, profiling is done using the net/http/pprof package and the runtime/pprof package.

To attach the profiler to an HTTP server, simply import:

import _ "net/http/pprof"

and start the HTTP server, for example:

import (
    "net/http"
    _ "net/http/pprof"
)

func main() {
    go func() {
        http.ListenAndServe(":6060", nil)
    }()
    // rest of the application code
}

After starting, you can take profiles by accessing the endpoints:

• http://localhost:6060/debug/pprof/profile — CPU profile (default 30 seconds)
• http://localhost:6060/debug/pprof/heap — memory profile
• http://localhost:6060/debug/pprof/goroutine — goroutine state

To programmatically record a CPU profile to a file:

import (
    "os"
    "runtime/pprof"
)

func main() {
    f, _ := os.Create("cpu.prof")
    pprof.StartCPUProfile(f)
    defer pprof.StopCPUProfile()

    // code to profile
}

Profiles are analyzed using the go tool pprof command.