This is a pretty old thread, but I wonder if anyone has tried something like this recently. I’m trying to profile a Phoenix app and I feel this should be easier. Here’s what I tried so far:

• iex -S mix phx.server
• :eprof.start_profiling([self()])
• Test the application
• :eprof.stop_profiling()
• :eprof.analyze(:total)

However, eprof does not log anything from the app itself. Using fprof though, I can get some calls to the application, but the summary format you get is pretty wild:

• iex -S mix phx.server
• :fprof.start()
• :fprof.trace([:start, procs: :all])
• Test the application
• :fprof.trace(:stop)
• :fprof.profile()
• :fprof.analyse(:totals)

You usually do not profile the running server. That would in best case only give you a profile of the connection acceptor, but not the spawned processes that actually handle the request.

You need to profile the actual controllers or views you are interested in.