first example crashes when starting Julia with multiple threads on apple silicon

[Eric Hanson]

In [2]: versioninfo()
Julia Version 1.9.2
Commit e4ee485e909 (2023-07-05 09:39 UTC)
Platform Info:
  OS: macOS (arm64-apple-darwin22.4.0)
  CPU: 8 × Apple M1
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-14.0.6 (ORCJIT, apple-m1)
  Threads: 4 on 4 virtual cores
Environment:
  JULIA_NUM_THREADS = 4
  JULIA_PKG_SERVER_REGISTRY_PREFERENCE = eager

(@mousetrap) pkg> st
Status `~/.julia/environments/mousetrap/Project.toml`
  [5deeb4b9] mousetrap v0.1.0 `https://github.com/Clemapfel/mousetrap.jl#main`
  [7f2654e2] mousetrap_apple_jll v0.1.0+0 `https://github.com/Clemapfel/mousetrap_apple_jll#main`
  [b6bb2801] mousetrap_linux_jll v0.1.0+0 `https://github.com/Clemapfel/mousetrap_linux_jll#main`
  [1923bf96] mousetrap_windows_jll v0.1.0+0 `https://github.com/Clemapfel/mousetrap_windows_jll#main`

In [4]: using mousetrap

In [5]: main() do app::Application
            window = Window(app)
            set_child!(window, Label("Hello World!"))
            present!(window)
        end

(process:93174): mousetrap.jl-WARNING **: 17:33:46.903: In mousetrap.main: You are running mousetrap from within the REPL. Interactive use of mousetrap is an experimental feature, side-effects may occurr.
Out[5]: Task (runnable) @0x000000010e68a590

In [6]:
(<unknown>:93174): GLib-GIO-CRITICAL **: 17:33:47.332: g_settings_schema_source_lookup: assertion 'source != NULL' failed

(<unknown>:93174): GLib-GIO-CRITICAL **: 17:33:47.332: g_settings_schema_source_lookup: assertion 'source != NULL' failed
2023-08-20 17:33:47.392 julia[93174:85063167] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'NSWindow drag regions should only be invalidated on the Main Thread!'
*** First throw call stack:
(
)
libc++abi: terminating with uncaught exception of type NSException

[93174] signal (6): Abort trap: 6
in expression starting at none:0
__pthread_kill at /usr/lib/system/libsystem_kernel.dylib (unknown line)
Allocations: 5301661 (Pool: 5298319; Big: 3342); GC: 8
zsh: abort      julia

If I start Julia with

JULIA_NUM_THREADS=1 julia

then the example works, although it doesn't render as nicely as in the README screenshot.

[Clem Cords]

Thank you, could you run the following code and tell me if it still crashes?

using mousetrap
app = Application("issue.test")
connect_signal_activate!(app) do app::Application
    window = Window(app)
    set_child!(window, Label("Test"))
    present!(window)
end
run!(app)

I will also try to reproduce this on my end

[Eric Hanson]

Thank you, could you run the following code and tell me if it still crashes?

This doesn't crash. No window pops up though. (BTW: I added a close-paren to the line set_child!(window, Label("Test"))

[Clem Cords]

Yes thank you, I typo'd there, also I forgot to add run!, this is the correct code, I also edited the original message.

using mousetrap
app = Application("issue.test")
connect_signal_activate!(app) do app::Application
    window = Window(app)
    set_child!(window, Label("Test"))
    present!(window)
end
run!(app)

Which should open a window.

Does this still crash for you? I apologize for the typos, I shouldn't be answering issue on my phone.

[Eric Hanson]

That works! It opens a window and does not crash.

[Clem Cords]

Okay thank you, I'm pretty sure usage of Threads.Task here is causing this then. I'll have a PR ready as soon as possible.

Until then you can just use that code snippet instead of main. Thank you for helping out!