go 1.9 Profiler labels

Profiler labels in Go

在Go 1.9中，加入了Profiler labels部分。

CPU profilers collect and output hot spots where the CPU spent most time in when executing

A typical CPU profiler output is primarily reports the location of these spots as function name, source file/line, etc

在以往的Go的调试过程中，性能问题的debug往往是最困难的。

With 1.9, Go is introducing a new feature that allows you to record additional information to provide more context about the execution path.

The runtime/pprof package will export several new APIs to let users add labels

关于打label部分:

labels := pprof.Labels("worker", "purge")
pprof.Do(ctx, labels, func(ctx context.Context) {
    // Do some work...

    go update(ctx) // propagates labels in ctx.
})

采用net/http/pprof来分析相关的性能，

package main

import _ "net/http/pprof"

func main() {
    // All the other code...
    log.Fatal(http.ListenAndServe("localhost:5555", nil))
}

通过

$ go tool pprof http://localhost:5555/debug/pprof/profile

首先通过tags区分出相关的path部分

(pprof) tags
http-path: Total 80
        70 (87.50%): /messages
        10 (12.50%): /user

worker: Total 158
       158 (  100%): purge

通过相关的filter部分，我们可以仅关注到/user部分

(pprof) tagfocus="http-path:/user"
(pprof) top10 -cum
Showing nodes accounting for 0.10s, 3.05% of 3.28s total
      flat  flat%   sum%        cum   cum%
         0     0%     0%      0.10s  3.05%  main.generateID.func1 /Users/jbd/src/hello/main.go
     0.01s   0.3%   0.3%      0.08s  2.44%  runtime.concatstring2 /Users/jbd/go/src/runtime/string.go
     0.06s  1.83%  2.13%      0.07s  2.13%  runtime.concatstrings /Users/jbd/go/src/runtime/string.go
     0.01s   0.3%  2.44%      0.02s  0.61%  runtime.mallocgc /Users/jbd/go/src/runtime/malloc.go
         0     0%  2.44%      0.02s  0.61%  runtime.slicebytetostring /Users/jbd/go/src/runtime/string.go
         0     0%  2.44%      0.02s  0.61%  strconv.FormatInt /Users/jbd/go/src/strconv/itoa.go
         0     0%  2.44%      0.02s  0.61%  strconv.Itoa /Users/jbd/go/src/strconv/itoa.go
         0     0%  2.44%      0.02s  0.61%  strconv.formatBits /Users/jbd/go/src/strconv/itoa.go
     0.01s   0.3%  2.74%      0.01s   0.3%  runtime.memmove /Users/jbd/go/src/runtime/memmove_amd64.s
     0.01s   0.3%  3.05%      0.01s   0.3%  runtime.nextFreeFast /Users/jbd/go/src/runtime/malloc.go

当然还有其他的命令

You can also use tagshow, taghide, and tagignore commands as other filtering options. For example, tagignore allows you to match anything but the given regex.

同时，注意pprofutil这个包