On Wed, Aug 24, 2011 at 4:30 AM, Markus Wanner <mar...@bluegap.ch> wrote: > I'm in respectful disagreement regarding the ring-buffer approach and > think that dynamic allocation can actually be more efficient if done > properly, because there doesn't need to be head and tail pointers, which > might turn into a point of contention.
True; although there are some other complications. With a sufficiently sophisticated allocator you can avoid mutex contention when allocating chunks, but then you have to store a pointer to the chunk somewhere or other, and that then requires some kind of synchronization. > As a side note: that I've been there with imessages. Those were first > organized as a ring-bufffer. The major problem with that approach was > the imessages were consumed with varying delay. In case an imessage was > left there for a longer amount of time, it blocked creation of new > imessages, because the ring-buffer cycled around once and its head > arrived back at the unconsumed imessage. > > IIUC (which might not be the case) the same issue applies for snapshots. One difference with snapshots is that only the latest snapshot is of any interest. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
