Robert Haas <robertmh...@gmail.com> writes: > On Tue, Dec 6, 2016 at 9:53 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> I think we should give serious consideration to back-patching commit >> ecb0d20a9, which changed the default semaphore type to unnamed-POSIX >> on Linux.
> Urk. That sounds like a scary thing to back-patch. I don't deny that it's scary, but the alternative seems to be to be rather badly broken on systemd-using distros for years to come. That's pretty scary too. > ... Granted, that might not > happen, because maybe unnamed POSIX semas are one of those really > awesome operating system primitives that never has problems on any > system anywhere ever. But I think it's pretty hard to be certain of > that. You're attacking a straw man. I didn't propose changing our behavior anywhere but Linux. AFAIK, on that platform unnamed POSIX semaphores are futexes, which have been a stable feature since 2003 according to https://en.wikipedia.org/wiki/Futex#History. Anybody who did need to compile PG for use with a pre-2.6 kernel could override the default, anyway. Now, I did think of a problem we'd have to deal with, which is how to avoid breaking ABI by changing sizeof(PGSemaphoreData). I think that's soluble though. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers