Re: RFC: C and concurrency (as CC extensions)

cr88192 wrote:
> general opinions with regards to sup****ting concurrency within a C
compiler.

This area is of course currently being developed by the C++
Standards Working Group, with cooperation/participation of the
C Standarfs Working Group.  The likely outcome will be some
form of threads (with shared memory).

The hardest technical issues have to do with the memory model.
It is not acceptable to require that shared memory be consistent
at all times between separate threads, because that isn't how
current multicore caching functions.  A volatile-qualified
access (and a sequence point) should suffice to flush out the
cache location, but it seems that many architectures will have
to flush an entire cache line at a time, which hurts performance.

Instead of threads, some consideration should be given to using
"channels", as described by Rob Pike in his Newsqueak article
and implemented in Plan 9 (in C) and Limbo (in Inferno).  This
is close to the Hoare CSP model and is easier to work with.