help: how to use gofuncgraph correctly

[hitzhangjie]

I have a golang program:

package main

import "time"

func main() {
  time.Sleep(time.Second)
}

then build go build -o main main.go

then run:

$ gofuncgraph --uprobe-wildcards='main.main' ./main 
found 3 uprobes, large number of uprobes (>1000) need long time for attaching and detaching, continue? [Y/n]
Y
INFO[0003] start tracing                                
^C
INFO[0009] start detachin

After 1 second, there's nothing output, I have to ctrl+c to terminate. I want to see the timecost duration execution of main.main.
Please help.

[jschwinger233]

$ sudo gofuncgraph --uprobe-wildcards 'main.main' ./gofunc_issue_2 'main.main'
found 3 uprobes, large number of uprobes (>1000) need long time for attaching and detaching, continue? [Y/n]
y
INFO[0002] start tracing                                

17 19:33:08.6581           main.main() { runtime.main+519 ?:?
17 19:33:09.6582 001.0001  } main.main+39 /home/gray/src/github.com/jschwinger233/proving-ground/gofunc_issue_2/main.go:7
^CINFO[0030] start detaching 

Steps:

1. sudo gofuncgraph --uprobe-wildcards 'main.main' ./main 'main.main'
2. in another terminal: ./main

Probably you thought gofuncgraph would execute the command automatically, it actually merely traces the binary, and you'll have to run the command manually.

Sorry for the misunderstanding, I've always been too lazy to work out an up-to-date and user-friendly documentation.

[jschwinger233]

BTW your tech blog helped me before, thanks a lot for those high-quality articles regarding ELF and debugger. 👍

[jschwinger233]

To be clear, the execution order is not required: in this case we have to run gofuncgraph ahead of ./main, otherwise we'll miss the invocation of main.main function.

For another scenario, for instance, if we'd like to trace grpc-related APIs inside a running daemon, just run gofuncgraph to attach the binary, then we can collect information from running process without disruption.

[hitzhangjie]

Thanks very much. It works.

[hitzhangjie]

I'm learning how to use ebpf and cilium.
gofuncgraph is not only a very nice tool but also a good learning material. 👍