Igor Kovalenko wrote:
> It does not have to be anonymous. POSIX also defines shm_open(same arguments
> as open) API which will create named object in whatever location corresponds
> to shared memory storage on that platform (object is then grown to needed
> size by ftruncate() and the fd is then passed to mmap). The object will
> exist in name space and can be detected by subsequent calls to shm_open()
> with same name. It is not really different from doing open(), but more
> portable (mmap() on regular files may not be supported).
Actually, I think the best shared memory implemention would be
MAP_ANON | MAP_SHARED mmap(), which could be called from the postmaster
and passed to child processes.
While all our platforms have mmap(), many don't have MAP_ANON, but those
that do could use it. You need MAP_ANON to prevent the shared memory
from being written to a disk file.
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill,
Pennsylvania19026
