Base.Filesystem concurrency for separate julia instances

New to Julia
, ,
1

The following MWE indicates that within a single julia instance:

  1. concurrent access to (thread-specific) sub-arrays is fine
  2. threaded IO via Base.Filesystem is fine
N = 2^20
checklens = Array{Array{Int64,1},1}(undef,Threads.nthreads())
for i in 1:length(checklens)
    checklens[i] = Array{Int64,1}(undef,0)
end
Threads.@threads for i in 1:N
    check=Base.Filesystem.readdir("/tmp/")
    push!(checklens[Threads.threadid()],length(check))
end
test 
@testset "single instance" begin
@test reduce(==,reduce(vcat,checklens))
@test length(reduce(vcat,checklens)) == N
end
Test Summary:   | Pass  Total
single instance |    2      2
Test.DefaultTestSet("single instance", Any[], 2, false)

Will this also work with separate (threaded) julia instances?
I’m not sure how to write a test for that.