[pgpool-general: 4540] Re: Pgpool - connection hangs in DISCARD ALL

Gerhard Wiesinger lists at wiesinger.com
Sat Mar 12 18:02:13 JST 2016 

Can you make new releases, at least for 3.4 and 3.5 branches to get them 
upstream.

Thnx.

Ciao,
Gerhard

-- https://www.wiesinger.com/


On 23.02.2016 13:27, Muhammad Usama wrote:
> On Tue, Feb 23, 2016 at 4:16 AM, Tatsuo Ishii <ishii at postgresql.org> wrote:
>> Usama,
>>
>> Doesn't pgpool-II 3.1 have the same problem?
> Sorry, I missed that and 3_0 aswell. I have pushed the same change to
> the both branches.
>
> Regards
> Muhammad Usama
>
>
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese:http://www.sraoss.co.jp
>>
>>> Hi
>>>
>>> I have pushed the above fix in all branches from pgpool-II 3.2 onwards.
>>> http://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=6afacb1b19603b37e3d005963182258b9f4fca49
>>>
>>> Thanks again for your help in verifying and testing the fix.
>>>
>>> Kind regards
>>> Muhammad Usama
>>>
>>>
>>> On Sat, Feb 20, 2016 at 1:03 AM, Muhammad Usama <m.usama at gmail.com> wrote:
>>>
>>>> Hi
>>>>
>>>> Many thanks for the confirmation, the fix needs to go in all branches and
>>>> I will push it in the morning.
>>>>
>>>> Regards
>>>> Muhammad Usama
>>>>
>>>> Sent from my iPhone
>>>>
>>>>> On 19-Feb-2016, at 11:52 PM, Gerhard Wiesinger <lists at wiesinger.com>
>>>> wrote:
>>>>> Hello,
>>>>>
>>>>> Can confirm that this patch worked for me (tested the 3.5 patch
>>>> version), nearly 2 days without any problem. Can you please add it to the
>>>> git repo and make a new release (3.4, 3.5).
>>>>> Thnx.
>>>>>
>>>>> Ciao,
>>>>> Gerhard
>>>>>
>>>>>
>>>>>> On 16.02.2016 11:44, Muhammad Usama wrote:
>>>>>> Hi
>>>>>>
>>>>>> Many thanks for the reply and a good news that you are not getting
>>>>>> stuck connection issue after the patch.
>>>>>>
>>>>>> Thanks
>>>>>> Best regards
>>>>>> Muhammad Usama
>>>>>>
>>>>>>
>>>>>>> On Fri, Feb 12, 2016 at 9:45 PM, Paweł Ufnalewski <archon at foap.com>
>>>> wrote:
>>>>>>> Hmm it looks like it's fine now. Right now I only see these in log:
>>>>>>>
>>>>>>> 2016-02-12 17:28:12: pid 8838: LOG:  child process with pid: 27299
>>>> exits
>>>>>>> with status 256
>>>>>>> 2016-02-12 17:28:12: pid 8838: LOG:  fork a new child process with
>>>> pid: 6140
>>>>>>> 2016-02-12 17:30:42: pid 8838: LOG:  child process with pid: 5571
>>>> exits with
>>>>>>> status 512
>>>>>>> 2016-02-12 17:30:42: pid 8838: LOG:  fork a new child process with
>>>> pid: 6720
>>>>>>> 2016-02-12 17:30:43: pid 8838: LOG:  child process with pid: 4444
>>>> exits with
>>>>>>> status 512
>>>>>>> 2016-02-12 17:30:43: pid 8838: LOG:  fork a new child process with
>>>> pid: 6751
>>>>>>> 2016-02-12 17:35:42: pid 8838: LOG:  child process with pid: 6140
>>>> exits with
>>>>>>> status 512
>>>>>>> 2016-02-12 17:35:42: pid 8838: LOG:  fork a new child process with
>>>> pid: 7868
>>>>>>> 2016-02-12 17:40:42: pid 8838: LOG:  child process with pid: 6751
>>>> exits with
>>>>>>> status 512
>>>>>>> 2016-02-12 17:40:42: pid 8838: LOG:  fork a new child process with
>>>> pid: 9018
>>>>>>> 2016-02-12 17:40:42: pid 8838: LOG:  child process with pid: 6720
>>>> exits with
>>>>>>> status 512
>>>>>>> 2016-02-12 17:40:42: pid 8838: LOG:  fork a new child process with
>>>> pid: 9019
>>>>>>> Thank you!
>>>>>>>
>>>>>>> Best regards,
>>>>>>> Paweł Ufnalewski
>>>>>>> Infrastructure Architect at Foap.com
>>>>>>>
>>>>>>> W dniu 2016-02-09 o 14:02, Muhammad Usama pisze:
>>>>>>>
>>>>>>>> Hi
>>>>>>>>
>>>>>>>> Many thanks for sharing the pgpool.log, The log shared by you does
>>>>>>>> contains some error messages "ERROR: unable to to flush data to
>>>>>>>> frontend" that have the potential to cause the stuck connection
>>>>>>>> Can you please try out the attached patch if it fix the problem. I am
>>>>>>>> attaching the patches for both 3_5 and 3_4 branches, please use the
>>>>>>>> respective patch as per your setup. Hopefully this should fix the
>>>>>>>> stuck issue.
>>>>>>>>
>>>>>>>> Kind regards
>>>>>>>> Muhammad Usama
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> On Mon, Feb 8, 2016 at 8:49 PM, Paweł Ufnalewski <archon at foap.com>
>>>> wrote:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>>       It looks like it hangs in this places (see attachment). Problem
>>>> is,
>>>>>>>>> that
>>>>>>>>> developer responsible for app has changed something in code, so
>>>>>>>>> connections
>>>>>>>>> now closes properly from client side (before I got a lot of these
>>>> errors:
>>>>>>>>> 2016-02-08 09:33:39: pid 8472: ERROR:  unable to read data from
>>>> frontend
>>>>>>>>> 2016-02-08 09:33:39: pid 8472: DETAIL:  EOF encountered with
>>>> frontend)
>>>>>>>>> .
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>> Paweł Ufnalewski
>>>>>>>>> Infrastructure Architect at Foap.com
>>>>>>>>>
>>>>>>>>> W dniu 2016-02-08 o 09:00, Muhammad Usama pisze:
>>>>>>>>>
>>>>>>>>> Hi
>>>>>>>>>
>>>>>>>>> Thanks in advance for the help. If you could share the pgpool-II log
>>>>>>>>> when the stuck connection happens that would help us in identifiny
>>>> and
>>>>>>>>> rectifing the problem.
>>>>>>>>>
>>>>>>>>> Thanks
>>>>>>>>> Best regards
>>>>>>>>> Muhammad Usama
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Mon, Feb 8, 2016 at 11:36 AM, Paweł Ufnalewski <archon at foap.com>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>>       just to let you know - I'm having the same problem with 3.4.4
>>>>>>>>> version
>>>>>>>>> (DISCARD ALL appears slower than in 3.4.3 I think, but it still
>>>> does).
>>>>>>>>> How
>>>>>>>>> can I help to fix this problem?
>>>>>>>>>
>>>>>>>>> Best regards,
>>>>>>>>> Paweł Ufnalewski
>>>>>>>>> Infrastructure Architect at Foap.com
>>>>>>>>>
>>>>>>>>> W dniu 2016-02-01 o 08:44, Muhammad Usama pisze:
>>>>>>>>>
>>>>>>>>> Hi Gerhard
>>>>>>>>>
>>>>>>>>> Many thanks for testing and pointing this out. It's unfortunate that
>>>> you
>>>>>>>>> are
>>>>>>>>> still getting the stuck connection issue. If it is possible can you
>>>>>>>>> please
>>>>>>>>> share the pgpool-II log for the time when this stuck connection issue
>>>>>>>>> happens. I am more interested in seeing which exact error message
>>>> that
>>>>>>>>> caused the child process to jump to error handler from where the
>>>> child
>>>>>>>>> process proceeded to send the DISCARD ALL to backend and eventually
>>>> got
>>>>>>>>> stuck. Since after many tries we are not able to reproduce this
>>>> issue, so
>>>>>>>>> log would be really helpful in understanding and fixing the problem.
>>>>>>>>>
>>>>>>>>> Best regards
>>>>>>>>> Muhammad Usama
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Sun, Jan 31, 2016 at 9:33 PM, Gerhard Wiesinger <
>>>> lists at wiesinger.com>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>> On 28.01.2016 01:10, Tatsuo Ishii wrote:
>>>>>>>>>
>>>>>>>>> On 21.01.2016 20:52, Muhammad Usama wrote:
>>>>>>>>>
>>>>>>>>> Hi
>>>>>>>>>
>>>>>>>>> I am looking into this issue. and unfortunately like Ishii-San I am
>>>>>>>>> also not able to reproduce it. But I found one issue in 3.4 that
>>>> might
>>>>>>>>> cause the problem. Can you please try the attached patch if it solves
>>>>>>>>> the problem. Also, if the problem still persists, it would be really
>>>>>>>>> helpful if you could share the pgpool-II log.
>>>>>>>>>
>>>>>>>>> I looked at the patch but it includes only logging changes and no
>>>>>>>>> functional changes. Therefore I didn't test it. Do you expect and
>>>>>>>>> behavioral changes to fix it, and why?
>>>>>>>>>
>>>>>>>>> elog() is not only a logging function, but also it plays very
>>>>>>>>> important role including exception handling and error treatments in
>>>>>>>>> pgpool-II. If you are familiar with PostgreSQL internals, you may
>>>>>>>>> notice it (elog() was imported from PostgreSQL source tree).
>>>>>>>>>
>>>>>>>>> Tried version 3.5.0 where the patch is included. Still not working.
>>>> See
>>>>>>>>> backtrace below.
>>>>>>>>>
>>>>>>>>> Reverting to 3.3.7 which works perfectly.
>>>>>>>>>
>>>>>>>>> Ciao,
>>>>>>>>> Gerhard
>>>>>>>>>
>>>>>>>>> (gdb) back
>>>>>>>>> #0  0x00007fd87fdb6d43 in __select_nocancel () from /lib64/libc.so.6
>>>>>>>>> #1  0x0000564471af16a1 in pool_check_fd (cp=cp at entry=0x564473dfa610)
>>>> at
>>>>>>>>> protocol/pool_process_query.c:635
>>>>>>>>> #2  0x0000564471af1976 in pool_check_fd (cp=cp at entry=0x564473dfa610)
>>>> at
>>>>>>>>> protocol/pool_process_query.c:657
>>>>>>>>> #3  0x0000564471b1f67b in pool_read (cp=0x564473dfa610,
>>>>>>>>> buf=buf at entry=0x7ffc1d71bf97, len=len at entry=1) at
>>>> utils/pool_stream.c:162
>>>>>>>>> #4  0x0000564471af8e6e in read_kind_from_backend
>>>>>>>>> (frontend=frontend at entry=0x564473df3e60,
>>>>>>>>> backend=backend at entry=0x564473df2e00,
>>>>>>>>>       decided_kind=decided_kind at entry=0x7ffc1d71c397 "E") at
>>>>>>>>> protocol/pool_process_query.c:3234
>>>>>>>>> #5  0x0000564471affdc9 in ProcessBackendResponse
>>>>>>>>> (frontend=frontend at entry=0x564473df3e60,
>>>>>>>>> backend=backend at entry=0x564473df2e00, state=state at entry
>>>> =0x7ffc1d71c41c,
>>>>>>>>>       num_fields=num_fields at entry=0x7ffc1d71c41a) at
>>>>>>>>> protocol/pool_proto_modules.c:2356
>>>>>>>>> #6  0x0000564471af5b15 in pool_process_query
>>>> (frontend=0x564473df3e60,
>>>>>>>>> backend=0x564473df2e00, reset_request=reset_request at entry=1) at
>>>>>>>>> protocol/pool_process_query.c:302
>>>>>>>>> #7  0x0000564471aed98c in backend_cleanup (backend=<optimized out>,
>>>>>>>>> frontend_invalid=frontend_invalid at entry=0 '\000',
>>>> frontend=0x564471e09e40
>>>>>>>>> <child_frontend>)
>>>>>>>>>       at protocol/child.c:437
>>>>>>>>> #8  0x0000564471af0637 in do_child (fds=fds at entry=0x564473dee030) at
>>>>>>>>> protocol/child.c:234
>>>>>>>>> #9  0x0000564471ace107 in fork_a_child (fds=0x564473dee030, id=8) at
>>>>>>>>> main/pgpool_main.c:678
>>>>>>>>> #10 0x0000564471aceb6d in reaper () at main/pgpool_main.c:2254
>>>>>>>>> #11 0x0000564471ad322b in PgpoolMain (discard_status=<optimized out>,
>>>>>>>>> clear_memcache_oidmaps=<optimized out>) at main/pgpool_main.c:429
>>>>>>>>> #12 0x0000564471acc7b1 in main (argc=<optimized out>,
>>>>>>>>> argv=0x7ffc1d7219e8)
>>>>>>>>> at main/main.c:310
>>>>>>>>>
>>>>>>>>> #1  0x0000564471af16a1 in pool_check_fd (cp=cp at entry=0x564473dfa610)
>>>> at
>>>>>>>>> protocol/pool_process_query.c:635
>>>>>>>>> 635                     fds = select(fd+1, &readmask, NULL,
>>>> &exceptmask,
>>>>>>>>> timeoutp);
>>>>>>>>>
>>>>>>>>> (gdb) print fd
>>>>>>>>> $1 = 8
>>>>>>>>> (gdb) print readmask
>>>>>>>>> $2 = {fds_bits = {256, 0 <repeats 15 times>}}
>>>>>>>>> (gdb) print exceptmask
>>>>>>>>> $3 = {fds_bits = {256, 0 <repeats 15 times>}}
>>>>>>>>> (gdb) print timeoutp
>>>>>>>>> $4 = (struct timeval *) 0x0
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> pgpool-general mailing list
>>>>>>>>> pgpool-general at pgpool.net
>>>>>>>>> http://www.pgpool.net/mailman/listinfo/pgpool-general
>>>>>> _______________________________________________
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