[pgpool-general: 4964] Re: PGPool Child Processes constantly dying

[Vlad Novikov]

Hello Steven,

Did you try enabling debugging mode (e.g. by running pgpool -n -d
1>logfile.log 2>&1 &) and adjusting the logging level in pgpool.conf? That
should provide more information about why the process is dying.

Regards,
Vlad

On Fri, Sep 2, 2016 at 1:54 AM, Steven Livingstone <steven at livz.org> wrote:

> Hi. I have a scenario where i have a connection pooling client
> (PGBouncer) making requests to PGPool and the child processes spun up
> by PGPool create segmentation faults, increasing in number over time
> until the client just gets errors.
>
> I am new to PGPool debugging and gdb in general, so any help much
> appreciated! I have turned off just about every advanced option in
> PGPool.conf over the last week but still can't get to the bottom of
> this.
>
> I did managed to create a backtrace of *something* by attaching to one
> of the child processes but in attaching to it, it doesn't die any more
> :-S As soon as i detach, it dies and there is a segfault as shown
> below (this is a small section ... i just get this constantly over
> time). .... i suspect i am missing something in how to trace properly.
>
> Sep  2 08:51:10 data-ha-node-0 pgpool[12573]: [7332-1] 2016-09-02
> 08:51:10: pid 12573: WARNING:  child process with pid: 31577 was
> terminated by segmentation fault
> Sep  2 08:51:10 data-ha-node-0 pgpool[12573]: [7333-1] 2016-09-02
> 08:51:10: pid 12573: LOG:  fork a new child process with pid: 31595
> Sep  2 08:51:10 data-ha-node-0 pgpool[31589]: [7331-1] 2016-09-02
> 08:51:10: pid 31589: LOG:  new connection received
> Sep  2 08:51:10 data-ha-node-0 pgpool[31589]: [7331-2] 2016-09-02
> 08:51:10: pid 31589: DETAIL:  connecting host=10.0.1.8 port=53526
> Sep  2 08:51:11 data-ha-node-0 kernel: [69483.710126] pgpool[31589]:
> segfault at ac ip 00000000004354a5 sp 00007fffffff91d0 error 4 in
> pgpool[400000+132000]
> Sep  2 08:51:11 data-ha-node-0 pgpool[12573]: [7334-1] 2016-09-02
> 08:51:11: pid 12573: WARNING:  child process with pid: 31589 was
> terminated by segmentation fault
> Sep  2 08:51:11 data-ha-node-0 pgpool[12573]: [7335-1] 2016-09-02
> 08:51:11: pid 12573: LOG:  fork a new child process with pid: 31601
> Sep  2 08:51:11 data-ha-node-0 pgpool[31595]: [7333-1] 2016-09-02
> 08:51:11: pid 31595: LOG:  new connection received
> Sep  2 08:51:11 data-ha-node-0 pgpool[31595]: [7333-2] 2016-09-02
> 08:51:11: pid 31595: DETAIL:  connecting host=10.0.1.8 port=53528
> Sep  2 08:51:11 data-ha-node-0 kernel: [69484.288433] pgpool[31595]:
> segfault at ac ip 00000000004354a5 sp 00007fffffff91d0 error 4 in
> pgpool[400000+132000]
> Sep  2 08:51:12 data-ha-node-0 pgpool[12573]: [7336-1] 2016-09-02
> 08:51:12: pid 12573: WARNING:  child process with pid: 31595 was
> terminated by segmentation fault
> Sep  2 08:51:12 data-ha-node-0 pgpool[12573]: [7337-1] 2016-09-02
> 08:51:12: pid 12573: LOG:  fork a new child process with pid: 31605
> Sep  2 08:51:12 data-ha-node-0 pgpool[31586]: [7329-1] 2016-09-02
> 08:51:12: pid 31586: LOG:  new connection received
>
>
>
>
>
> (gdb) bt
> #0  0x00007ffff717ac33 in select () from /lib/x86_64-linux-gnu/libc.so.6
> #1  0x0000000000426529 in wait_for_new_connections
> (saddr=0x7fffffff95c0, timeout=0x7fffffff9440, fds=0x7686c0) at
> protocol/child.c:1854
> #2  do_child (fds=fds at entry=0x7686c0) at protocol/child.c:295
> #3  0x00000000004076f5 in fork_a_child (fds=0x7686c0, id=1) at
> main/pgpool_main.c:678
> #4  0x00000000004080cc in reaper () at main/pgpool_main.c:2263
> #5  0x000000000040c2a9 in PgpoolMain
> (discard_status=discard_status at entry=0 '\000',
> clear_memcache_oidmaps=clear_memcache_oidmaps at entry=0 '\000') at
> main/pgpool_main.c:429
> #6  0x0000000000405f13 in main (argc=<optimized out>, argv=<optimized
> out>) at main/main.c:310
>
> Any ideas?
>
> /steven
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