[pgpool-general: 8887] Re: pgpool 4.4.2 error after upgrade

[Tatsuo Ishii]

Hi,

> Hi,
> 
> I recently upgraded pgpool from 4.1.1 to 4.4.2.  I saw in the pgpool logs
> this error.
> 
> 2023-07-08 00:39:20.825 [unknown] PROCESS: CHILD DB: pie2 USER:  APPL:
> [unknown] ERROR:  invalid memory alloc request size 18446744073709551592
> 2023-07-08 00:39:20.825 [unknown] PROCESS: CHILD DB: pie2 USER:  APPL:
> [unknown] CONTEXT:  while searching system catalog, When relcache is missed
> 
> When I google the error, it seems related to postgres.  However, when I
> look into the postgres logs, I do not see the error.  Also the logs in
> 4.1.1 do not have the same error.  I am unsure why I'm getting the error in
> 4.4.2.
> 
> The postgres is in version 14.5.  The db size is 1.4TB.  The OS is Ubuntu
> 20.  We installed pgpool from source.
> 
> wget https://www.pgpool.net/mediawiki/images/pgpool-II-4.4.2.tar.gz
> tar -xvzf pgpool-II-4.4.2.tar.gz
> cd pgpool-II-4.4.2/
> ./configure --prefix=/local/opt/points/pgpool4.4.2 --enable-sequence-lock
> make ; make install
> 
> I have attached the pgpool logs for both versions.
> 
> I hope to get clarity on what caused the error and how to resolve this.

In 4.4.x, pgpool stores system catalog information in shared memory
query cache by default. Unfortunately there's a known issue withe the
feature. It has been already fixed in this commit:
https://git.postgresql.org/gitweb/?p=pgpool2.git;a=commit;h=a091bcb4dece8b09089689a8fa775136f61e75df

So you have choices:

1) turn off the feature by "enable_shared_relcache = off" (you need to
restart pgpool). This may make the pgpool a littel bit slower because
each pgpool session needs to obtain the system catalog information
(unable to share the info in shared memory query cache).

2) wait for next 4.4.4 minor release. it is scheduled to release Aug
17th.

3) grab the latest source code from git repository.

Sorry for inconvenience.

BTW,

> ./configure --prefix=/local/opt/points/pgpool4.4.2 --enable-sequence-lock

You don't need "--enable-sequence-lock" option since you are using streaming replication mode.
(the option is only necessary for native replication mode and snapshot isolation mode).
--
Tatsuo Ishii
SRA OSS LLC
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp