How to profile phx.server?

Phoenix Forum Questions / Help
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1

I spent hours to find out how to profile phx.server (in dev). Without success.
I am looking for something link (pseudo code)
“mix with eprof run phx.server”
or something equivalent in iex
or some hook in the application code

2

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.

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3

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)
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