On Fri, Mar 12, 2021 at 7:55 PM Thomas Munro <thomas.mu...@gmail.com> wrote: > On Thu, Mar 11, 2021 at 7:34 PM Michael Paquier <mich...@paquier.xyz> wrote: > > Wow. This probably means that we would be able to get rid of > > USE_POSTMASTER_DEATH_SIGNAL? > > We'll still need it, because there'd still be systems with no signal: > NetBSD, OpenBSD, AIX, HPUX, illumos.
Erm, and of course macOS. There is actually something we could do here: ioctl(I_SETSIG) for SysV-derived systems and fcntl(O_ASYNC) for BSD-derived systems seems like a promising way to get a SIGIO signal when the postmaster goes away and the pipe becomes readable. Previously I'd discounted this, because it's not in POSIX and I doubted it would work well on other systems. But I was flicking through Stevens' UNIX book while trying to figure out that POLLHUP stuff from a nearby thread (though it's useless for that purpose) and I learned from section 12.6 that SIGIO is fairly ancient, originating in 4.2BSD, adopted by SVR4, so it's likely present in quite a few systems, maybe even all of our support platforms if we're prepared to do it two different ways. Just a thought.
