thread_local_vals.rb

### Thread.current is fiber local
f = Fiber.new do
  Thread.current[:foo] = 0
  loop do
    Fiber.yield(Thread.current[:foo])
    Thread.current[:foo] += 1
  end
end

f2 = Fiber.new do
  Thread.current[:foo] = 100
  loop do
    Fiber.yield(Thread.current[:foo])
    Thread.current[:foo] += 2
  end
end

5.times do
 p f.resume
 p f2.resume
end


# $ ruby thread_current.rb
# 0
# 100
# 1
# 102
# 2
# 104
# 3
# 106
# 4
# 108


### Global val case
f = Fiber.new do
  $foo = 0
  loop do
    Fiber.yield($foo)
    $foo += 1
  end
end

f2 = Fiber.new do
  $foo = 100
  loop do
    Fiber.yield($foo)
    $foo += 2
  end
end

5.times do
 p f.resume
 p f2.resume
end

# $ ruby global.rb
# 0
# 100
# 101
# 103
# 104
# 106
# 107
# 109
# 110
# 112