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

Tue Sep 20 16:08:01 UTC 2011

I tried to do that, but pgpool refuses to start reporting:
-bash: /usr/lib/debug/usr/sbin/pgpool.debug: bad ELF interpreter: No
such file or directory

I'm puzzled why it fails, as it was built on the same server where I
built the (working) release build of pgpool.

$ file /usr/lib/debug/usr/sbin/pgpool.debug
/usr/lib/debug/usr/sbin/pgpool.debug: ELF 64-bit LSB executable,
x86-64, version 1 (GNU/Linux), dynamically linked (uses shared libs),
for GNU/Linux 2.6.18, not stripped
$ file /usr/sbin/pgpool
/usr/sbin/pgpool: ELF 64-bit LSB executable, x86-64, version 1 (SYSV),
dynamically linked (uses shared libs), for GNU/Linux 2.6.18, stripped

On Mon, Sep 19, 2011 at 7:10 PM, Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
> 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.