Allowing Worker to spawn a different julia

[MichaelHatherly]

Currently Worker doesn't allow for setting the actual julia used, it always uses Base.julia_cmd().

Malt.jl/src/Malt.jl

Lines 103 to 105 in 37e4c4a

	function Worker(; env=String[], exeflags=[])
	# Spawn process
	cmd = _get_worker_cmd(; env, exeflags)

Malt.jl/src/Malt.jl

Lines 254 to 256 in 37e4c4a

	function _get_worker_cmd(exe=Base.julia_cmd()[1]; env, exeflags)
	return addenv(`$exe --startup-file=no $exeflags $(joinpath(src_path, "worker.jl"))`, String["OPENBLAS_NUM_THREADS=1", Base.byteenv(env)...])
	end

Would exposing that in the Worker constructor be something the maintainers would be happy to support? It appears to be needed to be able to support PumasAI/QuartoNotebookRunner.jl#42, which is something we'd like to add to the quarto runner.

---

Allowing for different julias does of course then run into the issue of serializing data between different versions not necessarily being deserializable by another julia. So that might warrant a separate issue to discuss being able to pick a different serialization method rather than using Serialization.serialize. I can open one for that if the issue of supporting julia selection for Worker is considered worth pursuing itself.

[pankgeorg]

Sitting next to @fonsp, Fons says great let's do it 😅

(proof: )

The custom serializer could also be a good idea

[MichaelHatherly]

Thanks, I'll see whether I can get a PR sorted sometime this week.