On Mon, 6 May 2002, Tom Lane wrote: > I said: > > But the backends would only have the socket open, they'd not be actively > > listening to it. So how could you tell whether anyone had the socket > > open or not? > > Oh, I take that back, I see how you could do it: the postmaster opens > the socket *for writing*, but never actually writes. All its child > processes inherit that same open file descriptor and just keep it > around. Then, to tell if anyone's home, you open the socket *for > reading* and try to read in O_NONBLOCK mode. You get an EOF indication > if and only if no one has the socket open for writing; otherwise you > get an EAGAIN error. > > That would work ... but is it more portable than depending on SysV > shmem connection counts? ISTR that some of the platforms we support > don't have Unix-style sockets at all.
Wouldn't the same thing work with a simple file? Does it have to be a UnixDomainSocket? ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
