Treat it as undefined. No two objects live at the same time will have
the same object id. That is the only guarantee.

Pavel Smerk wrote:
> Hello,
>
> assume some multithreaded application, thread1 starts and finishes, then
> thread2 starts --- how is the possibility that these two threads will
> have the same object_id? On what it depends?
> 
> Thanks,
> 
> P.