On Fri, Jul 1, 2011 at 11:44 AM, Hans-Peter Diettrich <drdiettri...@aol.com> wrote:
> IMO a linked list can not work flawlessly, until at least a > multiple-read-exclusive-write lock is used. While an exclusive-write lock > can ensure list consistency, every unsynchronized reader will be fooled by > concurrent changes to the list structure :-( I agree. Without a memory barrier, coupled with interlocked exchanges per node attachment, it would make memory synchronization impossible. > Consider what will happen when an (unsynchronized) reader determined an list > node, before or after which a new node shall be inserted. When the > write-synchronized update will happen, the list structure already can have > changed, so that the referenced node can have changed its position in the > list, or can have been moved into a very different list :-( Impossible to comprehend, that's why we have barriers. But in one specific case, Interestingly enough - the problem I experienced was with the 1 owning thread accessing the list. There was no subsequent access via additional threads, but across cores on a single cpu. _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
