Re: Posix Shared Mem patch

On Wed, Jun 27, 2012 at 9:52 AM, Stephen Frost <sfrost@snowman.net> wrote:
> What this all boils down to is- can you have a shm segment that goes
> away when no one is still attached to it, but actually give it a name
> and then detect if it already exists atomically on startup on
> Linux/Unixes?  If so, perhaps we could use the same mechanism on both..

As I understand it, no.  You can either have anonymous shared
mappings, which go away when no longer in use but do not have a name.
Or you can have POSIX or sysv shm, which have a name but do not
automatically go away when no longer in use.  There seems to be no
method for setting up a segment that both has a name and goes away
automatically.  POSIX shm in particular tries to "look like a file",
whereas anonymous memory tries to look more like malloc (except that
you can share the mapping with child processes).

-- 
Robert Haas
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