On 22/08/2009 19:52, hubert depesz lubaczewski wrote:
On Fri, Aug 21, 2009 at 04:26:11PM +0000, Sebastien Lardiere wrote:The following bug has been logged online:Bug reference: 5004 Logged by: Sebastien Lardiere Email address: slardi...@hi-media.com PostgreSQL version: 8.3.7 Operating system: Debian Etch Description: pg_freespacemap make a SegFault Details: I've got a crash with a cluster. Nothing found in the logfile, but a message about a Segfault, so I get a coredump and here is the backtrace :Can you check if you had any vacuums running at the time of crash?
Yes, autovacuum is on. it wasn't "normal" vacuum during the crash, but the last.
Nevertheless, the day before the first crash, I made a big delete on 23 millions of rows, and pg_freespacemap show a big increase of the number of pages in FSM. Then, when the number of pages in FSM increase, Pg crashes ; but :
It might be in logs, something like: WARNING: terminating connection because of crash of another server process DETAIL: The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory. HINT: In a moment you should be able to reconnect to the database and repeat your command. STATEMENT: vacuum if yes - how many vacuum jobs there were?
I never seen in the logs this messages with vacuum, Pg always crash with the query :
"select count(*) as pages from pg_freespacemap_pages" We can see in Munin ( graph attached ), the behavior :The big increase, then, the first crash, and, a each time there is a significat increase, a crash, with a reset of FSM.
I had disable the plugin, so there is no more queries with pg_freespacemap, and no crash.
-- Sébastien Lardière
<<attachment: bdd1-pg_fsm-week.png>>
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