Re: [boost] [xint] Third release is ready, requesting preliminary review

Subject: Re: [boost] [xint] Third release is ready, requesting preliminary review
From: Jeffrey Hellrung (jhellrung_at_[hidden])
Date: 2010-05-02 03:19:28

On 5/1/2010 11:44 PM, joel falcou wrote:
> Chad Nelson wrote:
>> If you're saying that people often write multithreaded programs, then I
>> have to disagree. In my experience, it's rare, and most programmers
>> actively avoid them.
> Plural of anedocte is not data.
> In genral, not taking multithreading seriously now is likely to be a
> problem in the upcoming years.
>
>>> Then it means you did somethign wrong or the code doesn't lend itself
>>> to trivial multithreading ...
> Sorry for the tone of that, I wasn't implying anything wrong with
> yourself, just that this
> kind of result (multithreaded version being slower) is usually because
> soemthing don't lend itself to
> be multithreaded. Do you have this MT code somewhere still, i may have a
> look if needed.
>

Chad, what Joel is referring to as "multithreaded" is really 
"thread-safe" in the context of your library, right?  I mean, not that 
Joel is using incorrect terminology on purpose, but maybe some terms and 
intents got confused during the discussion.  You (Chad) don't actually 
implement any distributed arithmetic algorithms, right?

Why do you need to link to Boost.Thread for the thread-safe version? I'm 
under the impression the thread-safe version does not use COW, so 
read-access shouldn't need to be serialized, which puts it at the same 
level of "thread safety" as the STL containers.  I don't see where 
Boost.Thread fits into this.  Do you have static data shared among all 
xint::integer instances?

Regarding COW specifically:  I'm guessing COW will be a tough sell, and 
I'm having a hard time swallowing that COW is 2x faster than (even 
emulated) move semantics.  Is the performance difference strictly from 
differing numbers of copy operations?  Can you identify (i.e., give an 
example of a real algorithm) where a move-enabled xint::integer produces 
more copies than a COW-enabled xint::integer?

- Jeff