Golang pprof live and in action

3 min readSep 15, 2021

Go `pprof` Live and in Action

pprof is a Go profiling tool.

There are a lot of Blogs on Go — pprof. Unfortunately, the code samples are pretty badly written or dont work off the bat. This code is a live working example of pprof in action.

You can find the code @ https://github.com/ArjunDhar/scribbles/tree/master/go-pprof-working

It show cases 2 modes.

Via net/http using the Web server routes in net/http/pprof.Init() -- WORKS
Using github.com/pkg/profile; this creates .out/mem.pprof file but it remains @ 0KB -- FAIL

Usage

Build & Run

go build -o sample.exe main.go
go run main.go

Access debug info

http://localhost:8082/debug/pprof/

Produce Memory Graph

Install Graphviz @ https://graphviz.org/download/ and ensure part of System PATH

go tool pprof -png http://localhost:8082/debug/pprof/heap > heap.png

Code notes

If you increase the ticker time to call clear(); you can crash the VM @ some point.

Sample Output

Following are generated by go tool command above

Sample CLI Out corresponding to above screens

D:\profiling-pprof\sample>go run main.go
[main]
[Profiler started]
2021/09/15 18:14:31 profile: memory profiling enabled (rate 4096), out\mem.pprof
[f()]
[net/http] WebServer started @ http://localhost:8082/debug/pprof/
[f->go] Timer fired : Clear slice[568187513] @  2021-09-15 18:15:31.1290589 +0530 IST m=+60.008981301
[clear]
[pre-clear] len= 568294570
[post-clear] len= 0
[f->go] Timer fired : Clear slice[294187520] @  2021-09-15 18:16:31.1291916 +0530 IST m=+120.009114001
[clear]
[pre-clear] len= 294187952
[post-clear] len= 0
[f->go] Timer fired : Clear slice[294187520] @  2021-09-15 18:17:31.1301379 +0530 IST m=+180.010060301
[clear]
[pre-clear] len= 294188396
[post-clear] len= 0
[f->go] Timer fired : Clear slice[573005841] @  2021-09-15 18:18:31.1291326 +0530 IST m=+240.009055001
[clear]
[pre-clear] len= 573227942
[post-clear] len= 0
[f->go] Timer fired : Clear slice[235350016] @  2021-09-15 18:19:31.1301378 +0530 IST m=+300.010060201
[clear]
[pre-clear] len= 235351899
[post-clear] len= 0
[f->go] Timer fired : Clear slice[459668480] @  2021-09-15 18:20:31.1298302 +0530 IST m=+360.009752601
[clear]
[pre-clear] len= 459669033
[post-clear] len= 0

Packages

github.com/pkg/profile
https://pkg.go.dev/github.com/pkg/profile
Go /http/pprof

References

These articles were the initial source, but they all have their own holes which are put together in my code