Re: [boost] Re: [Threads] Much faster try_mutex on Windows NT

From: Beman Dawes (bdawes_at_[hidden])
Date: 2004-03-24 21:12:24

At 12:59 AM 3/24/2004, John Torjo wrote:
 >David Abrahams wrote:
 >
 >>"Carl Daniel" <cpdaniel_at_[hidden]> writes:
 >>
 >>
 >>
 >>>Adal Chiriliuc wrote:
 >>>
 >>>
 >>>
 >>>>Wasn't event usage discouraged because it is unsafe?
 >>>>
 >>>>
 >>>That was semaphores.
 >>>
 >>>
 >>
 >>IIRC Windows Events have safety problems too.
 >>
 >>
 >>
 >I didn't know about that. Could you give a link or something, where such
 >problems are explained?
 >(right now I'm working no an app., and it uses a lot of Windows Events)

Semaphores were originally invented to overcome the problems of events. But 
Semaphores were only somewhat better, and so condition variables and 
various patterns were developed.

Dijkstra's 1965 paper "Cooperating Sequential Processes" explained the 
problems associated with events and any other constructs that depend on 
processing speed assumptions to work correctly. That paper was recently 
reprinted in the book "The Origin of Concurrent Programming", Per Brinch 
Hansen, editor, 2002.

Dijkstra died last year. Brinch Hansen and Hoare, the other giants of 
concurrent programming, are still active in computer science. Hoare has 
been knighted, the only programmer that I know of to gain that honor. 
Brinch Hansen has written some interesting recent papers pointing out 
problems with Java multi-tasking semantics.

--Beman