[pgpool-general: 9205] Re: Segmentation fault during shutdown

[Tatsuo Ishii]

> Thanks for the report.
> 
> Yes, it seems the crash happened when close_all_backend_connections()
> was called by on_exit which is called when process exits. I will look
> into this.

close_all_backend_connections() is responsible for closing pooled
connections to backend.  In the code MAIN_CONNECTION() macro is
used. Pooled connections could contain connections pointing to backend
which was valid at some point but is in down state at present. So
instead of MAIN_CONNECTION, we should use in_use_backend_id() here.
Attached patch does this. I hope the patch fixes your problem.

Best reagards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp

>> Hi,
>> 
>> One of our test runs this weekend hit another segmentation fault. This
>> crash seems to happen when pgpool is shutdown. This happens at the end of
>> the testcase that reverts a cluster back to a single node setup. At that
>> moment, 172.29.30.2 is already shutdown and removed from the cluster and
>> 172.29.30.3 is shutdown. The configuration is updated and pgpool on
>> 172.29.30.1 is restarted. The crash seems to happen at the moment ppgool on
>> 172.29.30.1 is shutdown to be restarted. I've got the feeling that the
>> simultaneous loss of .3 and the shutdown is causing this crash.
>> 
>> Below is the backtrace. Please not we've switched from Debian to Alpine
>> based images.
>> #0  0x000055fe4225f0ab in close_all_backend_connections () at
>> protocol/pool_connection_pool.c:1078
>> #1  0x000055fe422917ef in proc_exit_prepare (code=-1) at
>> ../../src/utils/error/elog.c:2707
>> #2  0x00007ff1af359da7 in __funcs_on_exit () at src/exit/atexit.c:34
>> #3  0x00007ff1af35108f in exit (code=code at entry=0) at src/exit/exit.c:29
>> #4  0x000055fe4224d4d2 in child_exit (code=0) at protocol/child.c:1378
>> #5  die (sig=3) at protocol/child.c:1174
>> #6  <signal handler called>
>> #7  memset () at src/string/x86_64/memset.s:55
>> #8  0x000055fe4225d2ed in memset (__n=<optimized out>, __c=0,
>> __d=<optimized out>) at /usr/include/fortify/string.h:75
>> #9  pool_init_cp () at protocol/pool_connection_pool.c:83
>> #10 0x000055fe4224f5f0 in do_child (fds=fds at entry=0x7ff1a6aabae0) at
>> protocol/child.c:222
>> #11 0x000055fe42223ebe in fork_a_child (fds=0x7ff1a6aabae0, id=11) at
>> main/pgpool_main.c:863
>> #12 0x000055fe42229d90 in exec_child_restart (node_id=0,
>> failover_context=0x7ffcd98e8c50) at main/pgpool_main.c:4684
>> #13 failover () at main/pgpool_main.c:1739
>> #14 0x000055fe42228cd9 in sigusr1_interrupt_processor () at
>> main/pgpool_main.c:1507
>> #15 0x000055fe4222900f in check_requests () at main/pgpool_main.c:4934
>> #16 0x000055fe4222ce53 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:649
>> #17 0x000055fe42222713 in main (argc=<optimized out>, argv=<optimized out>)
>> at main/main.c:365
>> 
>> Best regards,
>> Emond
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