Re: Parallel Seq Scan - Mailing list pgsql-hackers

Hi,

this is the backtrace:
gdb /var/lib/pgsql/9.6/data/ /var/lib/pgsql/9.6/data/core.7877
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-64.el7
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<http://www.gnu.org/software/gdb/bugs/>...
/var/lib/pgsql/9.6/data/: Success.
[New LWP 7877]
Missing separate debuginfo for the main executable file
Try: yum --enablerepo='*debug*' install /usr/lib/debug/.build-id/02/20b77a9ab8f607b0610082794165fccedf210d
Core was generated by `postgres: postgres tpcds [loca'.
Program terminated with signal 11, Segmentation fault.
#0  0x0000000000490b56 in ?? ()
(gdb) bt full
#0  0x0000000000490b56 in ?? ()
No symbol table info available.
#1  0x0000000000003668 in ?? ()
No symbol table info available.
#2  0x00007f956249a008 in ?? ()
No symbol table info available.
#3  0x000000000228c498 in ?? ()
No symbol table info available.
#4  0x0000000000000001 in ?? ()
No symbol table info available.
#5  0x000000000228ad00 in ?? ()
No symbol table info available.
#6  0x0000000000493fdf in ?? ()
No symbol table info available.
#7  0x00000000021a8e50 in ?? ()
No symbol table info available.
#8  0x0000000000000000 in ?? ()
No symbol table info available.
(gdb) q

Is there something else I can do?

On Mon, Nov 16, 2015 at 8:59 PM, Robert Haas <robertmhaas@gmail.com> wrote:

On Mon, Nov 16, 2015 at 2:51 PM, Bert <biertie@gmail.com> wrote:
> I've just pulled and compiled the new code.
> I'm running a TPC-DS like test on different PostgreSQL installations, but
> running (max) 12queries in parallel on a server with 12cores.
> I've configured max_parallel_degree to 2, and I get messages that backend
> processes crash.
> I am running the same test now with 6queries in parallel, and parallel
> degree to 2, and they seem to work. for now. :)
>
> This is the output I get in /var/log/messages
> Nov 16 20:40:05 woludwha02 kernel: postgres[22918]: segfault at 7fa3437bf104
> ip 0000000000490b56 sp 00007ffdf2f083a0 error 6 in postgres[400000+5b5000]
>
> Is there something else I should get?

Can you enable core dumps e.g. by passing the -c option to pg_ctl
start?  If you can get a core file, you can then get a backtrace
using:

gdb /path/to/postgres /path/to/core
bt full
q

That should be enough to find and fix whatever the bug is.  Thanks for testing.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

--

Bert Desmet
0477/305361