can't understand why code do not working

[Cliff via Digitalmars-d-learn]

On Monday, 22 September 2014 at 21:24:58 UTC, monarch_dodra wrote:
> On Monday, 22 September 2014 at 21:19:37 UTC, Steven 
> Schveighoffer wrote:
>> On 9/22/14 4:37 PM, Cliff wrote:
>>
>>>
>>> Is stdout threadsafe?
>>
>> Yes, stdout is thread safe, it's based on C's stdout which is 
>> thread safe.
>>
>> -Steve
>
> Techinallly, though thread "safe", concurrent writes will 
> create garbled text. D goes one step further in the sense that 
> it prevents concurrent writes entirely.

The reason I ask is that the first iteration of his loop does not 
show up in stdout as presented.  I would expect 1 and 3 to be the 
first two lines of the output.