RE: [boost] Re: Boost.Threads: Do we need all those mutexes?

From: Glen Knowles (gknowles_at_[hidden])
Date: 2004-07-10 16:48:25

> From: Howard Hinnant [mailto:hinnant_at_[hidden]] 
> On Jul 9, 2004, at 11:00 PM, Glen Knowles wrote:
> 
> >> <nod>  I just implemented lock_both::lock two ways:  Once 
> just keep 
> >> try-locking both ways, and once locking in the order of 
> the addresses 
> >> of the locks (with only two locks in the test, this was a safe 
> >> operator<).  My test looks like:
> >
> > The problem case for spinning is when one thread gets the locks and 
> > the holds them for a non-trivial length of time. During 
> that time the 
> > other, spinning thread, just wastes cpu as fast as it can. 
> This just 
> > gets magnified as more threads are involved.
> 
> You are describing a spin-lock, but not lock_both (except for 
> a theoretical and unlikely scenario).

Yes, I didn't think it through all the way.

Glen