[pgpool-general: 4483] Re: Pgpool - connection hangs in DISCARD ALL
Tatsuo Ishii
ishii at postgresql.org
Tue Feb 23 08:16:01 JST 2016
Usama,
Doesn't pgpool-II 3.1 have the same problem?
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
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>> _______________________________________________
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