We occasionally see $SUBJECT in the buildfarm, and I've also recently had reports of them from Red Hat customers. The obvious theory is that these reflect high load preventing the stats collector from responding, but it would really take pretty crushing load to make that happen if there were not anything funny going on.
It struck me just now while reviewing the latch code that pg_usleep could sleep for less than the expected time if a signal happened, and if that happened repeatedly for some reason, perhaps the loop could complete in much less than the nominal time. I'm not sure I believe that idea either, but anyway I'm feeling motivated to try to gather more data. Does anyone have a problem with sticking a lot of debugging printout into backend_read_statsfile() in HEAD only? I'm envisioning it starting to dump assorted information including elapsed time, errno values, etc once the loop counter is more than halfway to expiration, which is already a situation that we shouldn't see under normal conditions. 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