On Tue, Jan 21, 2014 at 2:58 PM, Noah Misch <n...@leadboat.com> wrote: >> What do people prefer? > > I recommend performing cleanup on the control segment named in PGShmemHeader > just before shmdt() in PGSharedMemoryCreate(). No new ERROR or WARNING sites > are necessary. Have dsm_postmaster_startup() continue to perform a cleanup on > the control segment named in the state file.
I think I'm on board with the first two sentences of this, but after Fujii Masao's email yesterday, I can't help thinking that what you propose the third sentence is a bad idea. He cloned a master to create a standby server on the same machine, and the standby startup ate the master's dynamic shared memory. We could teach pg_basebackup not to copy the state file, but that wouldn't help people who take base backups using the file system copy method, which is a lot of people. >> 5. Give up on this approach. We could keep what we have now, or make >> the DSM control segment land at a well-known address as we do for the >> main segment. > > How would having the DSM control segment at a well-known address affect the > problem at hand? Did you mean a well-known dsm_handle? Yeah. So the idea is that we'd always use a dsm_handle of 1000000 + (100 * port) or something like that, and then search forward until we find a dsm_handle that works. This is basically the same algorithm we're using today for the main shared memory segment, but with a large additive constant so that they don't collide with each other. -- 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
