The go 1.5 trace command

Question

The Go 1.5 release note says,

The new "go tool trace" command enables the visualisation of program traces generated by new tracing infrastructure in the runtime.

This is really exciting, and I want to know more about it. But its official document at https://golang.org/cmd/trace/ is really dry.

Found that Rob Pike complained about it, requesting that "shortly after the 1.5 release, there should be a blog post about the feature."

If anyone has posted/spotted such a blog, please add a link here. Or, if you like to answer directly here, it is also welcome as well.

Thanks

Answer 1

There are two ways you can generate trace files.

Method 1

1. Add following line at the start of your program

   f, err := os.Create(time.Now().Format("2006-01-02T150405.pprof"))
   if err != nil {
       panic(err)
   }
   defer f.Close()
   
   if err := trace.Start(f); err != nil {
       panic(err)
   }
   defer trace.Stop()
   

2. build the program

   go build

3. Run your program (for example ./myprogram)
4. Run go trace.

   go tool trace myprogram 2015-08-21T115354.pprof

Method 2

1. Write a testing function utilizing testing package.

2. Run Test with trace flag

   go test -trace trace.out

3. Run trace tool with generated .test and .out file

   go tool trace pkg.test trace.out

In both cases your browser will open something like this