From: "Iñaki Baz Castillo" <ibc@...>
Date: 2012-06-11T00:33:25+09:00
Subject: Re: Is "a,b=c,d" atomic? or do I need a Mutex?

2012/6/10 Iñaki Baz Castillo <ibc@aliax.net>:
> Hi, I have two methods that could be called by different threads and
> both use the same array:
>
>  def method1 object
>    MyModule.array << object
>  end
>
>  def method2
>    array, MyModule.array = MyModule.array, nil
>  end
>
> Do I need a Mutex (#synchronize() method) here? I think the answer is
> NOT since both actions in the array are "atomic". Am I right?

Auto-reply: Yes, it's atomic:

  def test a,b ;  $a, $b = a, b ;  end
  times = 10000000
  t1 = Thread.new { 1.upto(times) do |i| test(i,i) end }
  t2 = Thread.new { 1.upto(times) { raise "NOT EQUAL" if $a!=$b } }
  t1.join
  t2.join
  puts "OK"

=> "OK"

-- 
Iñaki Baz Castillo
<ibc@aliax.net>