Can't precompile without a display

[GlenHertz]

I'm using remote VSCode to a remote ssh backend and trying to precompile ProfileView but it fails with:

Failed to precompile ProfileView [c46f51b8-102a-5cf2-8d2c-8597cb0e0da7] to "/home/glenhertz/.julia/compiled/v1.10/ProfileView/jl_Ay2Daz".
ERROR: LoadError: InitError: Cannot open display: 
Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] Gtk.GLib.GError(f::Gtk.var"#325#331")
    @ Gtk.GLib ~/.julia/packages/Gtk/oo3cW/src/GLib/gerror.jl:17
  [3] __init__()
    @ Gtk ~/.julia/packages/Gtk/oo3cW/src/Gtk.jl:142
  [4] register_restored_modules(sv::Core.SimpleVector, pkg::Base.PkgId, path::String)
    @ Base ./loading.jl:1074
  [5] _include_from_serialized(pkg::Base.PkgId, path::String, ocachepath::String, depmods::Vector{Any})
    @ Base ./loading.jl:1020
...

Should ProfileView compile when no display is available?

[timholy]

I've wondered about that. But how would you use it without a display?

[timholy]

Looking at the stacktrace, the error is thrown from Gtk's __init__ function. So simply having Gtk as a dependency and loading the module seems to cause this.

[AmarnathMurugan]

I've wondered about that. But how would you use it without a display?

I've SSHed into a cluster from VS Code to use Julia, and get the same error. It is because GTK is checking the number of displays only on the remote node instead of my local device.

[alex-s-gardner]

This is an issue for myself as well. When using VSCode remote desktop ssh'd into a headless server I'm unable to use ProfileView because of GTK .

[jwahlstrand]

I think I see a path to get precompiling to not fail (or at least fail silently) without a display, by allowing the call of gtk_init_check in Gtk4's __init__ function to fail, and then in ProfileView.jl (and other downstream packages) checking if initialization succeeded before trying to run Gtk4-related code. But if downstream packages didn't check for initialization they would probably crash during precompilation, and the added complexity might lead to other problems.

Even if precompilation didn't error out on a headless server, GTK-based code isn't going to work through ssh without setting up something like X forwarding. Unless I'm missing something? Can you use VSCode's built-in @profview, which is not based on GTK?

[alex-s-gardner]

VSCode's built-in @profview does indeed work for my use case.

[deszoeke]

Failing at compile time creates problems for modules that perform image analyses on headless HPC nodes, and also provide methods to visualize data and results with an interactive session.

Are properties of the display needed for the compilation to work properly, or is it just checking because a display will be needed later? An error for no display is needed at run time. Perhaps a warning is appropriate at compile time.

Dependent ImageView also fails to compile for this reason.

[jwahlstrand]

The most effective technique for precompilation in Julia is using PrecompileTools and calling code to trigger compilation of relevant methods. Unfortunately, calling any code that creates Gtk4 widgets requires gtk_init_check to succeed -- otherwise you get a segfault. Right now, if the call of gtk_init_check in Gtk4's __init__ returns false, an error is thrown to remove the possibility of segfaulting for this reason.

The only solution I see is allowing the Gtk4 check to fail (with a warning to let users know about the danger of calling Gtk4 code) and then in downstream modules, doing precompilation only if initialization succeeded. The cost will be TTFX for those downstream modules (if precompilation was done while e.g. accessing the system through an SSH connection).