[pgpool-general: 4295] Re: Pgpool - connection hangs in DISCARD ALL

[Gerhard Wiesinger]

On 04.01.2016 10:00, Tatsuo Ishii wrote:
>>>>>>> On 31.12.2015 10:50, Tatsuo Ishii wrote:
>>>>>>>>> Yes, reconfigured. Keep you up2date. Any fix for the logic possible?
>>>>>>>> Yes, I'm thinking now.
>>>>>>> Still hangs even with child_max_connections = 0, same stack trace.
>>>>>> Too bad. I'm going to look for other causes if any.
>>>>> I remebered this:
>>>>>
>>>>> http://git.postgresql.org/gitweb/?p=pgpool2.git;a=commit;h=78d2fe3fd
>>>>> 82b4d2ee90e1369be8dd583196fd36e
>>>>>
>>>>> If you still have the problem after disabling client_idle_limit, the
>>>>> fix is for you.
>>> Sorry, I wanted to say:
>>>
>>>> If you do not  have the problem after disabling client_idle_limit,
>>>> the fix is for you.
>>>> Thnx, but still happens. Should I try master version or 3.3.7?
>>> That's an option. However, if you like, could you try the fix before
>>> going to 3.3?  The patch may fix other code path which trigger the
>>> problem.  (or try 3.4-stable head).
>>>
>> I tried the fix on the link already, but it didn't help (unless you did forget to attach another fix?).
>>
>> Will try 3.4-stable head, then 3.3 if it doesn't help.

3.4 stable head also has the problem:
(gdb) ba
#0  0x00007f53d6f40d63 in __select_nocancel () from /lib64/libc.so.6
#1  0x000055a2f00669e1 in pool_check_fd (cp=cp at entry=0x55a2f05c0a20) at 
protocol/pool_process_query.c:970
#2  0x000055a2f0066c86 in pool_check_fd (cp=cp at entry=0x55a2f05c0a20) at 
protocol/pool_process_query.c:992
#3  0x000055a2f00a9f7b in pool_read (cp=0x55a2f05c0a20, 
buf=buf at entry=0x7ffc811e7137, len=len at entry=1) at utils/pool_stream.c:159
#4  0x000055a2f006f1dc in read_kind_from_backend 
(frontend=frontend at entry=0x55a2f05ba270, 
backend=backend at entry=0x55a2f05b9210, 
decided_kind=decided_kind at entry=0x7ffc811e7537 "E")
     at protocol/pool_process_query.c:3618
#5  0x000055a2f0076d79 in ProcessBackendResponse 
(frontend=frontend at entry=0x55a2f05ba270, 
backend=backend at entry=0x55a2f05b9210, state=state at entry=0x7ffc811e75cc,
     num_fields=num_fields at entry=0x7ffc811e75ca) at 
protocol/pool_proto_modules.c:2519
#6  0x000055a2f006b1b7 in pool_process_query (frontend=0x55a2f05ba270, 
backend=0x55a2f05b9210, reset_request=reset_request at entry=1) at 
protocol/pool_process_query.c:302
#7  0x000055a2f0062a9a in backend_cleanup (backend=<optimized out>, 
frontend_invalid=frontend_invalid at entry=0 '\000', 
frontend=0x55a2f037c4e0 <child_frontend>) at protocol/child.c:442
#8  0x000055a2f0065745 in do_child (fds=fds at entry=0x55a2f05b4440) at 
protocol/child.c:238
#9  0x000055a2f004263e in fork_a_child (fds=0x55a2f05b4440, id=3) at 
main/pgpool_main.c:678
#10 0x000055a2f0043735 in reaper () at main/pgpool_main.c:2148
#11 0x000055a2f004724b in PgpoolMain (discard_status=<optimized out>, 
clear_memcache_oidmaps=<optimized out>) at main/pgpool_main.c:411
#12 0x000055a2f0040d4e in main (argc=<optimized out>, 
argv=0x7ffc811ecb28) at main/main.c:310

Will try 3.3.7.

BTW: I'm using the following script to get an overview whats happening:
cat watch_pg.sh
#!/usr/bin/env bash
watch -n 1 "ps wwwaux --sort=user,command,pid | grep -v grep | grep -E 
'^USER|pgpool|postgres:'"

Ciao,
Gerhard