v1.19.0-rc.1 - compilation does not finish with for comprehension in Ecto.Migrator anomymous function

[kevinschweikert]

Elixir and Erlang/OTP versions

Erlang/OTP 28 [erts-16.1] [source] [64-bit] [smp:11:11] [ds:11:11:10] [async-threads:1] [jit]

Elixir 1.19.0-rc.1 (f642b30) (compiled with Erlang/OTP 28)

Erlang 28.1

Operating system

macOS

Current behavior

After trying to compile our production app, the compilation never (i canceled it after ten minutes) on an Apple M3 processor.

> time mix compile
....
Compiling 142 files (.ex)
Verifying MyApp.Seeds (it's taking more than 10s)
^C
BREAK: (a)bort (A)bort with dump (c)ontinue (p)roc info (i)nfo
       (l)oaded (v)ersion (k)ill (D)b-tables (d)istribution
^C
________________________________________________________
Executed in  716.14 secs    fish           external
   usr time  708.74 secs    0.34 millis  708.74 secs
   sys time    4.90 secs    1.71 millis    4.90 secs

In our production app we have a seed.ex file. When i remove it the compilation finishes almost instantly.

I could reduce the issue down to a for comprehension in the Ecto.Migrator anomymous function

defmodule MyApp.Seeds do
  def seed() do
    Ecto.Migrator.with_repo(MyApp.Repo, fn repo ->
      for i <- 1..100//1 do
        %MyApp.SomeSchema{
          some_field: "foo",
          some_assocs: [
            %MyApp.SomeOtherSchema{
              field_1: "bar",
            }
          ]
        }
        |> repo.insert!()
      end
    end)
  end
end

Expected behavior

Reasonable compilation times. Let me know if i should add more information!

[kevinschweikert]

Oh one thing to add: Elixir 1.19-rc.0 works fine

> rm -rf _build/ && time mix compile
________________________________________________________
Executed in   19.43 secs    fish           external
   usr time   13.99 secs  141.00 micros   13.99 secs
   sys time    3.65 secs  580.00 micros    3.65 secs

[josevalim]

Thank you for the reproducer. This makes our lives much easier!!!

[josevalim]

Hi @kevinschweikert! I tried to reproduce the issue but failed. Here is the repo I have:

https://github.com/josevalim/ts_reprod

Can you reproduce it by bringing some of the code/structs from your app into it? Also try matching the ecto versions by copying your mix.lock over the repository and then doing mix deps.unlock --unused to prune it.

Thanks!

[kevinschweikert]

Hey @josevalim,

i opened up a PR. I found out that i just have to add phoenix_live_view and req and suddenly the compilation of MyApp.Seed slows down significantly. I don't know if this is caused by the dependencies or that they are just big enough and throw some type warnings. Let me know if you need anything else!

josevalim/ts_reprod#1

[moomerman]

We're seeing the same behaviour in our app (compilation doesn't complete), not that helpful but might give some clues:

staging 4m 35.5s » time mix compile
Compiling 959 files (.ex)
Generating App.Cldr for 2 locales named [:en, :und] with a default locale named :en

09:20:57.930 [warning] App.Cldr: The CLDR provider module Cldr.Date does not implement the function cldr_backend_provider/1
Compiling lib/app/explanations.ex (it's taking more than 10s)
Verifying AppWeb.DrillLive.Build (it's taking more than 10s)
Verifying AppWeb.OnboardingLive (it's taking more than 10s)
Verifying AppWeb.Billing.TutoringPricingComponent (it's taking more than 10s)
Verifying AppWeb.OfficialScoresComponent (it's taking more than 10s)
Verifying Mix.Tasks.Benchmarking.SeedTestData (it's taking more than 10s)
Verifying App.ScoreEstimation (it's taking more than 10s)
^C
BREAK: (a)bort (A)bort with dump (c)ontinue (p)roc info (i)nfo
       (l)oaded (v)ersion (k)ill (D)b-tables (d)istribution
^C
________________________________________________________
Executed in  150.99 secs    fish           external
   usr time  829.33 secs    0.38 millis  829.32 secs
   sys time   40.95 secs    1.58 millis   40.95 secs

Elixir 1.19-rc.0 is fine

[josevalim]

@moomerman can you please try #14813?

[moomerman]

the main branch doesn't compile for us due to an issue with faker dep but I cherry-picked 3163e4c onto v1.19 and it compiles now:

* 7f72ded04 - (HEAD -> v1.19) Fix optimizations for closed map checking (3 minutes ago) <José Valim>
* c06b6a929 - (origin/v1.19) Update ORT Scanner (#14594) (3 hours ago) <Jonatan Männchen>

[josevalim]

Ok, should do a new release soon, once we have more confirmation this is working for everyone. :)

[kevinschweikert]

Funny thing! I tried main on our production app and the compile time slow down went away! Yay! But the reproduction repo still gives me slow compile times

> rm -rf _build && ../../personal/elixir/bin/mix compile
Compiling 1 file (.ex)
Verifying MyApp.Seeds (it's taking more than 10s)
Generated foo app

[sabiwara]

I tried and it worked fine for me, I think it needs to be ../../personal/elixir/bin/elixir -S ../../personal/elixir/bin/mix compile.

I'm getting

compile --force  0.69s user 0.69s system 200% cpu 0.687 total

[kevinschweikert]

Thanks @sabiwara that did the trick! I just don't understand why :)

[sabiwara]

Good question, I've been using it without understanding myself 😄
But mix is actually just:

#!/usr/bin/env elixir

Mix.CLI.main()

So it wouldn't pick your local version of elixir by itself.