On 2015-12-25 13:28:55 -0500, Tom Lane wrote: > Hmm. And all those FDs point to the same pipe. I wonder if we're looking > at contention for some pipe-related data structure inside the kernel.
Sounds fairly likely - and not too surprising. In this scenario we've a couple 100k registrations/unregistrations to a pretty fundamentally shared resource (the wait queue for changes to the pipe). Not that surprising that it becomes a problem. There's a couple solutions I can think of to that problem: 1) Use epoll()/kqueue, or other similar interfaces that don't require re-registering fds at every invocation. My guess is that that'd be desirable for performance anyway. 2) Create a pair of fds between postmaster/backend for each backend. While obviously increasing the the number of FDs noticeably, it's interesting for other features as well: If we ever want to do FD passing from postmaster to existing backends, we're going to need that anyway. 3) Replace the postmaster_alive_fds socketpair by some other signalling mechanism. E.g. sending a procsignal to each backend, which sets the latch and a special flag in the latch structure. Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
