[Pgpool-general] seemingly hung pgpool process consuming 100% CPU

Tue Sep 20 02:10:58 UTC 2011

It's really hard to find the cause of the problem from a stack trace
without symbol tables... Is it possible to reinstalll pgpool binary
with debug symbols?
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> This happened again.  I ran the gdb command that you requested,
> however it occurred to me that the output may not be all that useful
> since I'm not running a debug build of pgpool:
> ###############
> # gdb pgpool 2343
> GNU gdb (GDB) Red Hat Enterprise Linux (7.1-29.el6)
> Copyright (C) 2010 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:
> <http://www.gnu.org/software/gdb/bugs/>...
> Reading symbols from /usr/sbin/pgpool...(no debugging symbols found)...done.
> Attaching to program: /usr/sbin/pgpool, process 2343
> Reading symbols from /usr/lib64/libpq.so.5...(no debugging symbols
> found)...done.
> Loaded symbols for /usr/lib64/libpq.so.5
> Reading symbols from /usr/lib64/libpcp.so.0...(no debugging symbols
> found)...done.
> Loaded symbols for /usr/lib64/libpcp.so.0
> Reading symbols from /lib64/libpam.so.0...(no debugging symbols found)...done.
> Loaded symbols for /lib64/libpam.so.0
> Reading symbols from /usr/lib64/libssl.so.10...(no debugging symbols
> found)...done.
> Loaded symbols for /usr/lib64/libssl.so.10
> Reading symbols from /usr/lib64/libcrypto.so.10...(no debugging
> symbols found)...done.
> Loaded symbols for /usr/lib64/libcrypto.so.10
> Reading symbols from /lib64/libcrypt.so.1...(no debugging symbols found)...done.
> Loaded symbols for /lib64/libcrypt.so.1
> Reading symbols from /lib64/libresolv.so.2...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/libresolv.so.2
> Reading symbols from /lib64/libnsl.so.1...(no debugging symbols found)...done.
> Loaded symbols for /lib64/libnsl.so.1
> Reading symbols from /lib64/libm.so.6...(no debugging symbols found)...done.
> Loaded symbols for /lib64/libm.so.6
> Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done.
> Loaded symbols for /lib64/libc.so.6
> Reading symbols from /lib64/libgssapi_krb5.so.2...(no debugging
> symbols found)...done.
> Loaded symbols for /lib64/libgssapi_krb5.so.2
> Reading symbols from /usr/lib64/libldap_r-2.4.so.2...(no debugging
> symbols found)...done.
> Loaded symbols for /usr/lib64/libldap_r-2.4.so.2
> Reading symbols from /lib64/libpthread.so.0...(no debugging symbols
> found)...done.
> [Thread debugging using libthread_db enabled]
> Loaded symbols for /lib64/libpthread.so.0
> Reading symbols from /lib64/libaudit.so.1...(no debugging symbols found)...done.
> Loaded symbols for /lib64/libaudit.so.1
> Reading symbols from /lib64/libdl.so.2...(no debugging symbols found)...done.
> Loaded symbols for /lib64/libdl.so.2
> Reading symbols from /lib64/libkrb5.so.3...(no debugging symbols found)...done.
> Loaded symbols for /lib64/libkrb5.so.3
> Reading symbols from /lib64/libcom_err.so.2...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/libcom_err.so.2
> Reading symbols from /lib64/libk5crypto.so.3...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/libk5crypto.so.3
> Reading symbols from /lib64/libz.so.1...(no debugging symbols found)...done.
> Loaded symbols for /lib64/libz.so.1
> Reading symbols from /usr/lib64/libfreebl3.so...(no debugging symbols
> found)...done.
> Loaded symbols for /usr/lib64/libfreebl3.so
> Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging
> symbols found)...done.
> Loaded symbols for /lib64/ld-linux-x86-64.so.2
> Reading symbols from /lib64/libkrb5support.so.0...(no debugging
> symbols found)...done.
> Loaded symbols for /lib64/libkrb5support.so.0
> Reading symbols from /lib64/libkeyutils.so.1...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/libkeyutils.so.1
> Reading symbols from /usr/lib64/liblber-2.4.so.2...(no debugging
> symbols found)...done.
> Loaded symbols for /usr/lib64/liblber-2.4.so.2
> Reading symbols from /usr/lib64/libsasl2.so.2...(no debugging symbols
> found)...done.
> Loaded symbols for /usr/lib64/libsasl2.so.2
> Reading symbols from /lib64/libselinux.so.1...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/libselinux.so.1
> Reading symbols from /lib64/libnss_files.so.2...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/libnss_files.so.2
> Reading symbols from /lib64/libnss_dns.so.2...(no debugging symbols
> found)...done.
> Loaded symbols for /lib64/libnss_dns.so.2
> 0x000000000044790a in ?? ()
> Missing separate debuginfos, use: debuginfo-install pgpool-II-3.0.4-1.el6.x86_64
> (gdb) bt
> #0  0x000000000044790a in ?? ()
> #1  0x0000000000414547 in ?? ()
> #2  0x000000000041762e in ?? ()
> #3  0x000000000040a4cd in ?? ()
> #4  0x0000000000405345 in ?? ()
> #5  0x00000000004068dc in ?? ()
> #6  0x00000000004076dc in ?? ()
> #7  0x00000031ae41ec5d in __libc_start_main () from /lib64/libc.so.6
> #8  0x0000000000403bf9 in ?? ()
> #9  0x00007fff0663cfc8 in ?? ()
> #10 0x000000000000001c in ?? ()
> #11 0x0000000000000004 in ?? ()
> #12 0x00007fff0663d90b in ?? ()
> #13 0x00007fff0663dfe6 in ?? ()
> #14 0x00007fff0663dfe6 in ?? ()
> #15 0x00007fff0663dfe6 in ?? ()
> #16 0x0000000000000000 in ?? ()
> (gdb) cont
> Continuing.
> 
> ###############
> 
> The entire session completely hung at the end there.
> 
> 
> On Wed, Sep 14, 2011 at 3:57 PM, Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
>> Please use gdb. For example,
>>
>> become postgres user (or root user)
>> gdb pgpool 29191
>> bt
>> cont
>> bt
>> cont
>> :
>> :
>> :
>>
>> This will give us an idea where it's looping.
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese: http://www.sraoss.co.jp
>>
>>> This problem has returned yet again:
>>>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>>> 29191 postgres  20   0 80192  14m 1544 R 89.8  0.2  51:15.91 pgpool
>>>
>>> postgres 29191  3.4  0.1  80192 14728 ?        R    Sep13  51:40
>>> pgpool: lfriedman nightly 10.31.96.84(61698) idle
>>>
>>>
>>> I'd really appreciate some input on how to debug this.
>>>
>>>
>>> On Fri, Sep 9, 2011 at 8:11 AM, Lonni J Friedman <netllama at gmail.com> wrote:
>>>> No one else has experienced this or has suggestions how to debug it?
>>>>
>>>> On Wed, Sep 7, 2011 at 12:49 PM, Lonni J Friedman <netllama at gmail.com> wrote:
>>>>> Greetings,
>>>>> I'm running pgpool-3.0.4 on a Linux-x86_64 server serving as a load
>>>>> balancer for a three server postgresql-9.0.4 cluster (1 master, 2
>>>>> standby).  I'm seeing strange behavior where a single pgpool process
>>>>> seems to hang after some period of time, and then consume 100% of the
>>>>> CPU.  I've seen this behavior happen twice since last Friday (when
>>>>> pgpool was brought online in my production environment).  At the
>>>>> moment the current hung process looks like this in 'ps auxww' output:
>>>>>
>>>>> postgres 19838 98.7  0.0  68856  2904 ?        R    Sep06 1027:36
>>>>> pgpool: lfriedman nightly 10.31.45.20(58277) idle
>>>>>
>>>>>
>>>>> In top, I see:
>>>>>  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>>>>> 19838 postgres  20   0 68856 2904 1072 R 100.0  0.0   1027:29 pgpool
>>>>>
>>>>>
>>>>> When to connect to the process with strace, there is no output, so I'm
>>>>> guessing the process is stuck spinning somewhere:
>>>>> # strace -p 19838
>>>>> Process 19838 attached - interrupt to quit
>>>>> ...
>>>>> ^CProcess 19838 detached
>>>>>
>>>>> One thing that i'm certain of is that the client IP (10.31.45.20)
>>>>> associated with the hung process has rebooted at least once since that
>>>>> process was spawned.  So pgpool seems to be in some confused state, as
>>>>> the client definitely severed the connection already.  I checked the
>>>>> pgpool log and there are no explicit references to PID 19838.  I'm at
>>>>> a loss how to debug this further, but clearly something is wrong
>>>>> somewhere, and this isn't normal/expected behavior.