Ruby Recursion

recursion.rb

def rec i
  if i==10000
    return i
  else
    i=i+1
    rec(i)   
  end
end

x = rec(2)

puts "#{x}"

$>>ruby recursion.rb
$>>recursion.rb:2: stack level too deep (SystemStackError)

resursion.rb

def rec i
  if i==1000
    return i
  else
    i=i+1
    rec(i)   
  end
end

x = rec(2)

puts "#{x}"

$>>ruby recursion.rb
$>>1000