Re: [boost] shared_ptr in multithreaded environments

From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2008-03-11 14:59:12

Peter Dimov wrote
> Mathias Gaunard:
> 
>> I see that shared_ptr is quite costly in multithreaded environments 
>> cause it would need DCAS, and thus uses a spinlock in cases where it is 
>> not available.
> 
> Where do you see that? It's not true.

AFAIK, the current shared_ptr is not lock-free at all.
Discussion about making it lock-free said it required to use DWCAS 
(cmpxchg16b on x86-64). It seems, however, this wasn't implemented.