Warnings during precompilation on v1.10-beta1: `waiting for IO to finish`

[nickrobinson251]

When precompiling a large private package, on v1.10-beta1, i see these warnings:

FilePathsBase Waiting for background task / IO / timer.
[pid 18736] waiting for IO to finish:
 TYPE[FD/PID]       @UV_HANDLE_T->DATA
 timer              @0x600002cbed00->0x10da90ee0
Mocking Waiting for background task / IO / timer.
[pid 18734] waiting for IO to finish:
 TYPE[FD/PID]       @UV_HANDLE_T->DATA
 timer              @0x600000c43c00->0x10d71c1f0

Precompilation continues and completes successfully, but i do not know how to fix these warning...

• Is this pointing to some issue within Julia (or Pkg)? Or is it an issue in these packages?
• If this is pointing to an issue in these packages, please could we have a clearer warning message? (i.e. how do i go fix them?)

[vtjnash]

It is not a warning, just an informational statement that the package is using sleep in some place that is slowing down precompilation. It may not be easy to find the offending package, since Julia doesn't really know why the package called sleep, just that it is now stuck waiting for it to complete before it can get back to doing useful work.

[nickrobinson251]

thanks for the explanation!

So perhaps more of a user-experience question... why are we showing this to every user if it's not problematic or (realistically) actionable? Right now it's a kinda gnarly/scary looking thing

Could we just not log this info? or at least make it opt-in? or dependent on how long we've been waiting? or...?

[timholy]

The same warning can be issued for precompilation job that will block forever unless fixed: comonicon/Comonicon.jl#249

[brenhinkeller]

FWIW, it gets called a warning on-screen -- also seems to be associated with this glitch of the progress bar:

[ViralBShah]

I have seen that warning on a few occasions, and I was wondering that unless the system wants me to do something about it, why show it?

[timholy]

In some cases things are only being held open transiently. Could we delay showing the warning a bit longer?

[vtjnash]

That they are held open at all is usually at least a small mistake, since the program should be closing them explicitly when done with them.

[sloede]

I'm getting these warnings on a regular basis as well, including with Julia v1.10.0-beta2. E.g., from pkg> add Trixi OrdinaryDiffEq, I get

Precompiling project...
  194 dependencies successfully precompiled in 92 seconds. 10 already precompiled.
  3 dependencies had warnings during precompilation:
┌ SummationByPartsOperatorsDiffEqCallbacksExt [82d7d246-636b-5c42-a4f7-7a8a453087a7]
│  [pid 720185] waiting for IO to finish:
│   TYPE[FD/PID]       @UV_HANDLE_T->DATA
│   timer              @0x107c040->0x7f8e2e0e9060
└
┌ LinearMapsStatisticsExt [364b1850-867c-5a65-9f2f-642d093ba2f6]
│  [pid 704422] waiting for IO to finish:
│   TYPE[FD/PID]       @UV_HANDLE_T->DATA
│   timer              @0x261b550->0x7f6d92ae8f10
└
┌ ExponentialUtilities [d4d017d3-3776-5f7e-afef-a10c40355c18]
│  [pid 712737] waiting for IO to finish:
│   TYPE[FD/PID]       @UV_HANDLE_T->DATA
│   timer              @0x955b000->0x7f9e61c56230
└

Is there a problem with Trixi.jl or OrdinaryDiffEq.j? Can the user do something about it?

• If yes, could we improve the messages such that they are more helpful?
• If not, could we just not show them anymore (they look scary!)?

[vtjnash]

Yes, it means one of their dependencies is using a Timer to handle some sort of event, and that is quite possibly some sort of bug in those packages (e.g. a datarace somewhere) that may need to be fixed.

[sloede]

OK, thanks. Could you please clarify: Which package needs fixing? The one reported, the one that was originally installed, or one of the dependencies of the reported packages?

[timholy]

This is far more difficult to debug now than it should be, but see #50914 (which contains both documentation on how to fix now as well as a speculative change that might give us tools to make it somewhat easier).

[sloede]

Thanks for the hint!

I'd still argue that before v1.10 is released, it would be great if the warning message were downgraded to an info or made less scary looking, and would be more helpful on what to do/expect as a user.