> Linking pthreads into the backend is likely to cause more problems than > it solves, especially if you're proposing that we do that everywhere. > > regards, tom lane
No, I am not proposing that. Not linking to pthread when not needed should actually be an optimization since the libc noop stubs get used instead. I've found the issue now (yes, again :) Short version: FreeBSD compiles the main server and contrib modules without and with pthreads, respectively. No bug in postgresql. If you're in a hurry, no need to read any further. Longer version: With FreeBSD ports, the contrib part is compiled separately. For some reason, the contrib units are being made to link to pthread, but the server itself isn't. So the backend forks to handle a request, some stored procedure touches some XML, libxml2 thinks it is initializing some mutex by calling some pthread_ stubs in libc, the stored procedure updates a column which has a trigram index, postgresql dynamically loads pg_trgm.so, which links to libpthread, and now the weak libc symbols are overridden and a little bit later we end up calling a real pthread_ method passing a non-initialized mutex and get a bus error. Lots of fun to debug, seeing pthread_self() suddenly changing return value within a single thread/backend in the middle of processing a single request.. With a custom (correct) compilation everything functions correctly with an unmodified libxml2 and postgresql, and without any linking to or preloading libpthread. Question is, why are postgresql90-server and postgresql90-contrib compiled differently ? It seems it may have been intended as a quick fix for pgbench, as the configure script for the -contrib port does not end up with "-pthread" in the PTHREAD_CFLAGS in Makefile.global which breaks compilation of pgbench, the server does have this, haven't found the reason yet. Side effect is that all modules link to pthread while the server doesn't .. I will continue this discussion within FreeBSD, as this is not a PostgreSQL bug (though if there is ever a loadable contrib module which does need pthreads the above situation will occur again). Thanks again to all who helped! Cheers Dennis -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
