I am looking for a possibility to generate a call graph for Go projects. Something similar to Doxygen's diagram functionality for C++ classes (with the option CALL_GRAPH=YES).
So far I found
http://saml.rilspace.org/profiling-and-creating-call-graphs-for-go-programs-with-go-tool-pprof
or
http://blog.golang.org/profiling-go-programs
This samples the call stack of your program 100 times per second while the program is running and creates a graph useful for profiling. If your program spends most of its time in functions not relevant to you, I found this solution not very usefull.
Then there is this:
https://godoc.org/golang.org/x/tools/go/callgraph/static
which from its description sounds like what I would need, but there seem to be no docs and I don't understand how to use it.
I also found
https://github.com/davecheney/graphpkg/blob/master/README.md
and
https://github.com/paetzke/go-dep-graph/blob/master/README.org
but they create only dependency graphs.
Answer
Take a look here:
- http://dave.cheney.net/2014/10/22/simple-profiling-package-moved-updated
- https://github.com/pkg/profile
func main() {
defer profile.Start(profile.CPUProfile, profile.ProfilePath(".")).Stop()
// Rest of program
}
Build and run your program as per normal. You'll see the profiling hook mentioned:
2015/07/12 09:02:02 profile: cpu profiling enabled, cpu.pprof
Run your program (bench it, run through it, etc) to generate the profile during runtime. Once you've hit what you want, quit and then generate the call-graph:
go tool pprof -pdf -output cgraph.pdf $YOURPROGBINARY cpu.pprof
You can also run go tool pprof $YOURPROGBINARY cpu.pprof to get an
interactive prompt where you can call top10 or web to generate an svg. Type
help at the pprof prompt to get a list of commands.
e.g. - here's the CPU profile for a buffer pool implementation I wrote:
~/Desktop go tool pprof poolio cpu.pprof
Entering interactive mode (type "help" for commands)
(pprof) top5
24770ms of 35160ms total (70.45%)
Dropped 217 nodes (cum <= 175.80ms)
Showing top 5 nodes out of 74 (cum >= 650ms)
flat flat% sum% cum cum%
12520ms 35.61% 35.61% 12520ms 35.61% runtime.mach_semaphore_wait
9300ms 26.45% 62.06% 9360ms 26.62% syscall.Syscall
1380ms 3.92% 65.98% 2120ms 6.03% encoding/json.(*encodeState).string
1030ms 2.93% 68.91% 1030ms 2.93% runtime.kevent
540ms 1.54% 70.45% 650ms 1.85% runtime.mallocgc
And here's a quick way to generate a PNG from the prompt:
(pprof) png > graph.png
Generating report in graph.png
Which outputs this:
