`find_type` causes lock contention

[BioTurboNick]

JLD2.jl/src/data/reconstructing_datatypes.jl

Lines 324 to 339 in d144466

	function find_type(typepath::String)
	parts = split(typepath, '.')
	# Find a type in the loaded modules by traversing the parts
	for mod in Base.loaded_modules_array()
	for part in parts
	sym = Symbol(part)
	(!isa(mod, Module) || !isdefined(mod, sym)) && break
	mod = getfield(mod, sym)
	end
	if mod isa DataType || mod isa UnionAll
	# We found a type, so we can stop searching
	return mod
	end
	end
	return nothing
	end

Every call to find_type calls Base.loaded_modules_array, which 1) globally locks and 2) creates a fresh copy of the array.

Perhaps JLD2 could look up the loaded_modules_array just once on each loading call and carry that forward? (Is this a use case for ScopedValue?)