Re: FreeBSD 9.0/amd64, PostgreSQL 9.1.2, pgbouncer 1.4.2: segmentation fault

On 10.01.2012 17:22, Andrew Alcheyev wrote:
> At some point the backend with this client crashes due to segmentation
> fault with signal 11.
>
> GDB shows the following:
> #0 0x00000000006b3a5b in SHMQueueDelete (queue=0x845b4c498) at shmqueue.c:77
> 77 prevElem->next = queue->next;
> [New Thread 8025cd400 (LWP 100635/<unknown>)]
> [New LWP 100709]
> (gdb) bt
> #0 0x00000000006b3a5b in SHMQueueDelete (queue=0x845b4c498) at shmqueue.c:77
> #1 0x00000000006c16ef in SummarizeOldestCommittedSxact () at predicate.c:1467
> #2 0x00000000006c197f in RegisterSerializableTransactionInt (snapshot=0xbe7480) at predicate.c:1605
> #3 0x00000000006c190a in RegisterSerializableTransaction (snapshot=0xbe7480) at predicate.c:1569
> #4 0x00000000007ffcf7 in GetTransactionSnapshot () at snapmgr.c:138
> #5 0x00000000006cbaf5 in exec_simple_query (query_string=0x80249e030 "SELECT 'DBD::Pg ping test'") at postgres.c:932
> #6 0x00000000006cfcb3 in PostgresMain (argc=2, argv=0x80249a890, username=0x80249a860 "stat") at postgres.c:3926
> #7 0x000000000068340d in BackendRun (port=0x802448900) at postmaster.c:3601
> #8 0x0000000000682b1a in BackendStartup (port=0x802448900) at postmaster.c:3286
> #9 0x000000000067ff5c in ServerLoop () at postmaster.c:1455
> #10 0x000000000067f73d in PostmasterMain (argc=3, argv=0x7fffffffdb90) at postmaster.c:1116
> #11 0x00000000005fa67a in main (argc=3, argv=0x7fffffffdb90) at main.c:199
> (gdb) p prevElem
> $1 = (SHM_QUEUE *) 0x0

That clearly looks like a bug in the SSI feature, introduced in
PostgreSQL 9.1.

This looks superficically similar to the bug that Dan Ports spotted on
Friday:
http://www.mail-archive.com/pgsql-hackers(at)postgresql(dot)org/msg190135.html.
If you can reproduce the issue easily, could you try the patch he posted
and see if it fixes it?

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com