go tool pprof using application PID instead of http endpoint

Question

Right now, I profile Go applications using go tool pprof like this:

go tool pprof http://localhost:8080/debug/pprof/profile

I want to use the pprof tool on an arbitrary Go process which is running a http server on an unknown port. The only information I have about the process is its PID. I need to do one of two things:

• Get the Go processes port number from its PID.
• Profile the running process directly. For example, something like go tool pprof 10303 where the PID is 10303.

Would either of these work?

Answer 1

Service Discovery is designed to resolve problems like this. A simple solution is to create a tmp file for every PID, writing each port to the according file. and read the port when you need go tool pprof.

http.ListenAndServe("localhost:" + PORT, nil)
tmpFilePath := filePath.Join(os.TempDir(), "myport_" + strconv.FormatInt(os.Getpid(), 10))
f, _ := os.OpenFile(tmpFilePath, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
f.Write(byte[](strconv.FormatInt(PORT, 10)))
f.Close()

in go tool prof bash: go tool http://localhost:`cat /tmp/myport_10303`/debug/pprof/profile

not tested in real, maybe some syntax error

UPDATE:

another way not change go source is, use bash command like netstat/lsof to find out the listening port of the go process. like:

netstat -antp | grep 10303| grep LISTEN | awk '{ print $4 }' | awk -F: '{print $2}'

not best bash script I think, just for reference.