[pgpool-hackers: 2312] Segmentation fault in Pgpool child process

Muhammad Usama m.usama at gmail.com
Wed May 3 23:36:57 JST 2017

Hi Ishii-San

I am getting the segmentation fault in Pgpool-II child process on master
and 3_6 stable branches.

Steps to reproduce.

1-) Start the pgpool-II with two backend nodes (both PG up and running).
2-) Stop one backend node (bin/pg_ctl -D data_5432/ stop)
3-) pgpool-II will perform failover.
4-) Connect to Pgpool-II using PSQL after failover is done.

Step 4 is producing the segmentation fault

The configuration file I was using for testing is attached and see below
the stack trace.

--stack trace--

[usama at localhost pgpool]$ gdb --core /tmp/core_pgpool.97854 bin/pgpool
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-94.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:
Reading symbols from
[New LWP 97854]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `pgpool: usama postgres  idle
Program terminated with signal 11, Segmentation fault.
#0  0x0000000000422f21 in select_load_balancing_node () at
1669 char *database = MASTER_CONNECTION(ses->backend)->sp->database;
Missing separate debuginfos, use: debuginfo-install
audit-libs-2.6.5-3.el7.x86_64 cyrus-sasl-lib-2.1.26-20.el7_2.x86_64
glibc-2.17-157.el7.x86_64 keyutils-libs-1.5.8-3.el7.x86_64
krb5-libs-1.14.1-27.el7_3.x86_64 libcap-ng-0.7.5-4.el7.x86_64
libcom_err-1.42.9-9.el7.x86_64 libgcc-4.8.5-11.el7.x86_64
libmemcached-1.0.16-5.el7.x86_64 libselinux-2.5-6.el7.x86_64
libstdc++-4.8.5-11.el7.x86_64 nspr-4.13.1-1.0.el7_3.x86_64
nss-3.28.2-1.6.el7_3.x86_64 nss-softokn-freebl-
nss-util-3.28.2-1.1.el7_3.x86_64 openldap-2.4.40-13.el7.x86_64
openssl-libs-1.0.1e-60.el7_3.1.x86_64 pam-1.1.8-18.el7.x86_64
pcre-8.32-15.el7_2.1.x86_64 zlib-1.2.7-17.el7.x86_64
(gdb) bt
#0  0x0000000000422f21 in select_load_balancing_node () at
#1  0x000000000043d935 in pool_init_session_context (frontend=<optimized
out>, backend=<optimized out>) at context/pool_session_context.c:97
#2  0x0000000000423dee in do_child (fds=fds at entry=0xf41600) at
#3  0x00000000004087e5 in fork_a_child (fds=0xf41600, id=3) at
#4  0x000000000040bf6e in failover () at main/pgpool_main.c:1952
#5  0x000000000040ccce in sigusr1_interupt_processor () at
#6  0x000000000040df9a in PgpoolMain (discard_status=discard_status at entry=1
'\001', clear_memcache_oidmaps=clear_memcache_oidmaps at entry=0 '\000') at
#7  0x0000000000406dbe in main (argc=<optimized out>, argv=<optimized out>)
at main/main.c:300

Best Regards
Muhammad Usama
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