WordCount performance

[Sean Kelly]

== Quote from Benji Smith (benji at benjismith.net)'s article
> Walter Bright wrote:
> > Sean Kelly wrote:
> >> Another option might be to check the thread count is greater than
> >> 1 and only lock if it is.  Tango has a routine called thread_needLock
> >> for this purpose, though it goes a bit farther and is true once a
> >> thread has been created through program termination.  This avoids
> >> problems with the situation where you have multiple threads running
> >> and all but one terminate but memory is not yet synchronized.
> >
> > You have to be very careful with such schemes because they can run afoul
> > of the notoriously difficult to comprehend "double checked locking" bug.
> I thought the double-checked locking idiom was only buggy in the Java
> memory model (prior to being fixed in the 1.6 JDK).

It's broken in C++ as well.  It actually works in D however, provided one uses
'volatile' in the right places.  I posted a demo impl a few years back either in
this forum or in D.announce.


Sean