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Re: Parallel Seq Scan - Mailing list pgsql-hackers

From Bert
Subject Re: Parallel Seq Scan
Date
Msg-id CAFCtE1nfLLZx==ENn8_-+EaP9iOzd-3r657hZYp3uAAW7JkNFQ@mail.gmail.com
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In response to Re: Parallel Seq Scan  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: Parallel Seq Scan  (Bert <biertie@gmail.com>)
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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
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<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

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