Subj : Re: Challenge: Multithreading & Synchronization
To   : comp.programming.threads
From : David Schwartz
Date : Mon May 23 2005 12:11 pm


"doug" <noone@nowhere.co.uk> wrote in message 
news:ZyPje.1900$iq5.1180@fe1.news.blueyonder.co.uk...

> I know where you're coming from - that's where I came from too.  But some 
> folk (Peter, Giancarlo) explained that *yes*, you might read the wrong 
> value, but it doesn't matter.  You're guaranteed to get the answer to the 
> question "do I own this lock" correct.

    Guaranteed by what?

    Suppose you are thread "A1". The lock is held by "A2" and transfers to 
"B1" while you are checking the owner field. What stops you from seeing half 
of each and getting "A1", and thinking you own the lock?

    DS

.