Excerpts from Florian Pflug's message of mar dic 14 21:51:47 -0300 2010: > Hi > > When I run my FK concurrency test suite on an unpatched HEAD, I'm getting > quite a lot of "no unpinned buffers available" errors. > > Increasing shared_buffers from 32MB (the default) to 64MB makes the errors go > away, as does setting fsync=off. > > I'm not sure how many buffers a particular backend can hold at any time. I'd > have though it'd be something like one per relation and scan-in-progress, > with indices counting as relations. In that case, with max_connections=100, > my tests shouldn't pin more than a couple of hundred buffers at a time. That, > however, amounts to about 1MB or so of pinned buffers, so it shouldn't break > with shared_buffers=32MB. > > I'm also confused by fsync=off making a difference. That should make writing > dirty buffers slower, but would it affect the number of buffers pinned? > > In short, I'm wondering whether I might have hit a bug, or if I should just > increase shared_buffers and move on.
I remember a report of this problem some time ago, and I wasn't able to explain it -- my calculations said, like yours, that the maximum amount of pinned buffers I expected shouldn't have been enough to consume the whole pool. It would be good to trace down to the root cause. -- Álvaro Herrera <alvhe...@commandprompt.com> The PostgreSQL Company - Command Prompt, Inc. PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
