1. run the main.go using `go run main.go`
2. find the pid of the process and send a USR1 signal using `kill -USR1 pid-of-main`
3. the `heap_profile.pprof` will be generated in the directory the `main` process was running
4. run `go tool pprof -http=:8081 heap_profile.pprof` to visualize the heap