On Mon, 2012-07-23 at 11:09 -0400, Tom Lane wrote: > Jim Vanns <james.vanns@xxxxxxxxxxxxxx> writes: > > We're seeing SELECT statements and even EXPLAIN (no ANAYLZE) > > statements hang indefinitely until *something* (we don't know what) > > releases some kind of resource or no longer becomes a massive bottle > > neck. These are the symptoms. > > Does anything show up as blocked in the pg_locks view? Nope. > Could you attach to the stuck process with gdb and get a stack trace? Haven't been quite brave enough to do that yet - this is a production server. I did manage to strace a process though - it (the server side process of a psql EXPLAIN) appeared to spin on an awful lot of semop() calls with the occasional read(). Of course, in the context of a shared memory system such as postgres I'd expect to see quite a lot of semop() calls but I've no idea how much is normal and how much is excessive. Jim > regards, tom lane > -- Jim Vanns Systems Programmer Framestore -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
