How to speed up the start of `mix test`?

Questions / Help
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#1

I work on a very large umbrella project. I did this config in my web app:

config :logger,
  level: String.to_atom(System.get_env("LOGGER_LEVEL") || "info"),
  handle_otp_reports: true,
  handle_sasl_reports: true

config :my_web, MyWeb.Gettext, one_module_per_locale: true, allowed_locales: ["en"]

But finally, I found that when I was testing a file, it took almost 5 seconds before my gettext app started:

These are the top logs when I run mix test filename.exs at 11:10:30:

11:10:35.496 [info]  Child Gettext.ExtractorAgent of Supervisor #PID<0.4876.0> (Supervisor.Default) started
Pid: #PID<0.4877.0>
Start Call: Gettext.ExtractorAgent.start_link([])
Restart: :permanent
Shutdown: 5000
Type: :worker

then, I removed the gettext deps, but It doesn’t solve the problem.

These are the top logs when I run mix test filename.exs at 12:37:00 after I remove the gettext deps:

2021-10-31 12:37:04.800 [info] module=application_controller function=info_started/2 line=2089  Application logger started at :nonode@nohost
2021-10-31 12:37:04.844 [info] module=supervisor function=report_progress/2 line=1546  Child :ttb_autostart of Supervisor :runtime_tools_sup started
Pid: #PID<0.4893.0>

References

#2

You can run MIX_DEBUG=1 mix test and it will show you the timing to run tasks in recent Elixir versions. If you are on Elixir v1.11 or later and you have a Phoenix application running on latest v1.5 or v1.6, you can remove the :phoenix compiler in the :compilers option of your mix.exs. That should speed it up by 2-3s in large apps.

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#3

When I set MIX_DEBUG=1, Finally, I found that the time was mainly spent on loadpaths:

==> my_web
<- Ran mix deps.loadpaths in 2828ms
<- Ran mix loadpaths in 2830ms
#4

What is your Elixir version? We have recently sped it up, make sure to try the latest v1.12.

#5

Yes, I’ve used the latest version,

$ asdf list elixir
  1.12.3-otp-24
  ref:v1.12.3
$ asdf list erlang
  24.0.6

and I found this answer: `mix` even more slugish with Elixir 1.12.1

Maybe this problem is not easy to solve, looking forward to the arrival of Elixir 1.13 version.

#6

The fixes in that thread are already in place. Can you please post the full output of your mix command with the debug flag here?

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