[Pgpool-general] FW: Child process was terminated by segmentation fault
Tatsuo Ishii
ishii at sraoss.co.jp
Fri Nov 18 04:56:48 UTC 2011
> Thank you for your effort. The problem occurs almost always, but not every time, when the following SQL query is issued:
>
> UPDATE ahs_transaction SET end_timestamp = NOW(), response_code = $1 WHERE id = $2
I did some tests with code something like below:
PreparedStatement pstmt = null;
for (int i = 0; i < N; i++) {
connection.setAutoCommit(false);
pstmt = connection.prepareStatement("UPDATE ahs_transaction SET end_timestamp = NOW(), response_code = ? WHERE id = ?");
pstmt.setInt(1, i);
pstmt.setInt(2, i);
pstmt.executeUpdate();
pstmt.close();
connection.commit();
But had not seen crash.
> Where ahs_transaction table is defined as follows:
>
> CREATE TABLE ahs_transaction
> (
> ID BIGSERIAL NOT NULL PRIMARY KEY,
> start_timestamp TIMESTAMP NOT NULL DEFAULT NOW(),
> end_timestamp TIMESTAMP,
> request_ID INTEGER NOT NULL REFERENCES ahs_request(ID),
> response_code SMALLINT
> );
Because the table references another table, I removed the foreign key
when I did the test:
CREATE TABLE ahs_transaction
(
ID BIGSERIAL NOT NULL PRIMARY KEY,
start_timestamp TIMESTAMP NOT NULL DEFAULT NOW(),
end_timestamp TIMESTAMP,
request_ID INTEGER NOT NULL,
response_code SMALLINT
);
In summary, I could not reproduce your problem here. More details about my env:
OS: Linux kernel 2.6.35 x86_64
jdbc driver: postgresql-9.1-901.jdbc4.jar
PostgreSQL 9.1.1
java-1.6.0-openjdk-1.6.0.0-4.b22vl6.x86_64
It would be helpfull if you give me standalone sample Java program and
table (and data if neccessary) which can reproduce the proble.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp
> On this transaction our java application which is issuing the query receives an SQL exception (I/O error).
> I hope this helps. If I can help you with anything else, let me know.
> Regards,
>
> silvio
>
>
>
>
> -----Original Message-----
> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
> Sent: 17. studeni 2011 0:33
> To: Silvio Svečnjak
> Cc: pgpool-general at pgfoundry.org
> Subject: Re: [Pgpool-general] FW: Child process was terminated by segmentation fault
>
> Thanks. This backtrace is much better than mine (probably the best at
> this point). I'm going to debug using the info. In the mean time I
> might need additional info such as variable contents from the core. If
> it occurs, I will let you know. So please keep the core file
> executable file of pgpool and sources.
>
> Also if you know how to reproduce the problem, please let me know.
> With the info, I could reproduce the problem here and make it very
> easy(thus quickly) to find the cause of the bug. Because core is just
> the result of the bug, sometimes it is very hard to find the cause of
> the bug. Knowing how to reporduce the problem is the best way to find
> the cause.
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
>
>> 2 files I sent you were the backtrace from the core dump file ($ gdb /usr/local/bin/pgpool core-file + (gdb)bt). I have repeated the error and took the backtrace again (file is enclosed), but the backtrace is the same. How to get additional info in the backtrace?
>> Regards,
>>
>> silvio
>>
>>
>>
>> -----Original Message-----
>> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
>> Sent: 16. studeni 2011 12:41
>> To: Silvio Svečnjak
>> Cc: pgpool-general at pgfoundry.org
>> Subject: Re: [Pgpool-general] FW: Child process was terminated by segmentation fault
>>
>> Can you show me backtrace?
>>
>> $ gdb pgpool core-file
>> (gdb)bt
>>
>> I expect to get more usefull info because the core was generated by
>> your pgpool binary.
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese: http://www.sraoss.co.jp
>>
>>> Hello!
>>>
>>> Could you please clarify what would be more useful info for further analysis? Thanks,
>>>
>>> silvio
>>>
>>>
>>> -----Original Message-----
>>> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
>>> Sent: 16. studeni 2011 2:03
>>> To: Silvio Svečnjak
>>> Cc: pgpool-general at pgfoundry.org
>>> Subject: Re: [Pgpool-general] FW: Child process was terminated by segmentation fault
>>>
>>> Silvio,
>>>
>>> Thank you for sending cores. I got backtrace this:
>>>
>>> gdb .libs/pgpool ~/core-pgpool-11-0-0-20473-1321347122
>>> GNU gdb (GDB) 7.2
>>> 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-vine-linux".
>>> For bug reporting instructions, please see:
>>> <http://www.gnu.org/software/gdb/bugs/>...
>>> Reading symbols from /home/t-ishii/work/pgfoundry/pgpool-II-3.1/.libs/pgpool...done.
>>>
>>> warning: exec file is newer than core file.
>>> [New Thread 20473]
>>> Reading symbols from /lib64/ld-linux-x86-64.so.2...done.
>>> Loaded symbols for /lib64/ld-linux-x86-64.so.2
>>>
>>> warning: no loadable sections found in added symbol-file system-supplied DSO at 0x7fff50f70000
>>> Core was generated by `pgpool: vcms'.
>>> Program terminated with signal 11, Segmentation fault.
>>> #0 0x00000000004626ef in core_yylex_init (ptr_yy_globals=0x100) at scan.c:3444
>>> 3444 memset(*ptr_yy_globals,0x00,sizeof(struct yyguts_t));
>>> (gdb) bt
>>> #0 0x00000000004626ef in core_yylex_init (ptr_yy_globals=0x100) at scan.c:3444
>>> #1 0x00000000000000b2 in ?? ()
>>> #2 0x0000000000000050 in ?? ()
>>> #3 0x000000001c1978b0 in ?? ()
>>> #4 0x0000000000000000 in ?? ()
>>> (gdb)
>>>
>>> It seems the backtrace does not show too much usefull info. I think
>>> this is because the stack frame was trashed badly by a overrun of
>>> memory copy. I'm looking into the problem anyway but it would be great
>>> if you or someone provide me more usefull info...
>>> --
>>> Tatsuo Ishii
>>> SRA OSS, Inc. Japan
>>> English: http://www.sraoss.co.jp/index_en.php
>>> Japanese: http://www.sraoss.co.jp
>>>
>>>> Thanks for your quick response. Dump/trace files are enclosed - I hope they contain the information you need - if not please let me know what else could help you.
>>>> Regards,
>>>>
>>>> silvio
>>>>
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
>>>> Sent: 14. studeni 2011 16:05
>>>> To: Silvio Svečnjak
>>>> Cc: pgpool-general at pgfoundry.org
>>>> Subject: Re: [Pgpool-general] FW: Child process was terminated by segmentation fault
>>>>
>>>>> We're using pgpool 3.1 with PostgreSQL 8.4.7 on RHEL 5.3 x64 where pgpool is configured for replication only on 2 backends. Pgpool is used by a real time java application which occasionally (without any visible pattern) catches an exception (org.postgresql.util.PSQLException: An I/O error occured while sending to the backend).
>>>>>
>>>>>
>>>>>
>>>>> We've determined that the exception is caused by pgpool as at the same time pgpool records the following error:
>>>>>
>>>>>
>>>>>
>>>>> 2011-11-14 14:14:45 ERROR: pid 10783: Child process 10812 was terminated by segmentation fault
>>>>>
>>>>> 2011-11-14 14:14:45 DEBUG: pid 10783: child 10812 exits with status 11 by signal 11
>>>>>
>>>>>
>>>>>
>>>>> Bigger chunk of log file is enclosed as well as the pgpool configuration file.
>>>>>
>>>>>
>>>>>
>>>>> After some research on the mailing lists, I found that some patches have been released for version 3.1 which may resolve the issue. So I downloaded and deployed the latest stable release pgpool2-V3_1_STABLE-8b47d55, but it didn't solve the problem.
>>>>>
>>>>>
>>>>>
>>>>> I would appreciate very much if someone could provide any help with this? Thank you in advance,
>>>>
>>>> Can you take a core and show us the backtrace? It will be very helpfull.
>>>> --
>>>> Tatsuo Ishii
>>>> SRA OSS, Inc. Japan
>>>> English: http://www.sraoss.co.jp/index_en.php
>>>> Japanese: http://www.sraoss.co.jp
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