How to share function f() arguments with Threads.@spawn?

General Usage
1

Dear all,

First of all, sorry if element has been questioned before.

I have the following code with multi-threads ($ julia --threads=4 when launching Julia ): :

import Base.Threads.@spawn

mutable struct MyStructTest 
	a::Int
end

function test_spawn(nn::MyStructTest)
     #do some stuff related to nn.a
      return nn.a
  end
  
  m = MyStructTest(4);

  m1 = Threads.@spawn test_spawn(m);
  m.a = 6;
  m2 = Threads.@spawn test_spawn(m);
  m.a = 8;
  m3 = Threads.@spawn test_spawn(m);

fetch(m1)
fetch(m2)
fetch(m3)

and it produces:

julia> fetch(m1)
4

julia> fetch(m2)
8

julia> fetch(m3)
8

But with single thread :

julia> fetch(m1)
4

julia> fetch(m2)
6

julia> fetch(m3)
8

I am asking how to be sure that m1 is 4, m2 is 6 and m3 is 8 with multi-threading?

Warmest regards