Hi,
I've just managed to recover from a fun Postgres lock up experience!
Basically Postgres seemed to have hung, with a stack of idle postmaster
processes. There was an idle VACUUM process and an idle CHECKPOINT process
running as well.
I finally managed to get it restarted (after a reboot), then I ran vacuumdb
again to test it, ctrl-c'd it while it was running, and then ps ax was
showing an idle VACUUM process again!
I restarted the computer again and then vacuumdb ran to completion.
Some of my problems were related to the fact that we were using daemontools
to monitor the postgres process. I've taken that off now as I think it was
more trouble than it was worth.
The vacuum analyze that caused the original crash I think was in pg_amop. I
have a copy of the data dir from then if anyone's interested, and I can dig
into the logfiles a bit more to try to give more info...
Chris