Re: [Boost-users] [shared_ptr] locking issues in Multithreads andsinglethreaded env.

From: Peter Dimov (pdimov_at_[hidden])
Date: 2006-05-24 11:43:52

Kobi Cohen-Arazi wrote:
> Hi
>
> As far as we know, boost::shared_ptr has a locking overhead when
> inc/dec is invoked.
>
> I wonder:
> 1. Is it using atomic op?

It depends on the platform.

> 3. What can we do in order to be able to use shared_ptr without that
> overhead?

You can #define BOOST_SP_DISABLE_THREADS.

http://www.boost.org/libs/smart_ptr/shared_ptr.htm#ThreadSafety

> 2. Why Alexandrescu policy based shared_ptr was rejected?

A policy-based smart pointer never got to the "formal review" stage. David 
Held was very close to submitting one and has made a formal review request:

http://lists.boost.org/Archives/boost/2005/08/91848.php

but I don't remember what happened. Maybe he pulled it. However the Loki 
version is, I believe, actively maintained.

http://loki-lib.sourceforge.net/