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In-Reply-To: <20251130.102712.131456481338876013.ishii@postgresql.org>
From: zam bak <zam6ak@gmail.com>
Date: Mon, 1 Dec 2025 09:42:40 -0500
Message-ID: 
 <CAEy4EGXPw9cU6C6TSCK1FODs0ZK3P3COmsoGU69UFzWeip4b_w@mail.gmail.com>
Subject: Re: "buffer overflow detected" when running SHOW POOL_STATUS
To: Tatsuo Ishii <ishii@postgresql.org>
Cc: pgpool-general@lists.postgresql.org
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On Sat, Nov 29, 2025 at 8:27=E2=80=AFPM Tatsuo Ishii <ishii@postgresql.org>=
 wrote:
>
> Hello,
>
> Thank you for the report!
>
> Unfortunately, I was not able to reproduce the issue on my Ubuntu 24
> and Rocky Linux 10.1 box (pgpool is compiled from source code).
> So there are some questions:
>
> - Is the issue occurred even when you execute other pgpool command?
>   (for example "show pool_processes")

No. Only getting this issue when running SHOW POOL_STATUS

>
> - I found a problem with the output of "show pool_status". The value
>   of "memqcache_stats_start_time" is shown with newline and an empty
>   item followed. I am not sure if this is related to your issue. If
>   possible, can you please try the attached patch?

I suspect you want me to compile it from source (after applying this patch)=
.
I don't have the setup for this unfortunately.
As I mentioned, I did install from RPMs using Rocky Linux 10.1 (with
minimal install option)
Is there a way to provide RPM instead of the patch?


>
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS K.K.
> English: http://www.sraoss.co.jp/index_en/
> Japanese:http://www.sraoss.co.jp
>
> > Hello
> >
> > I am using the latest pgpool-II v4.6.4 on Rocky Linux v10.1
> > (installation via RPMs) with PostgreSQL 18 (one primary, one replica,
> > streaming replication)
> > When attempting to run POOL_STATUS command, either as SQL or via pcp,
> > I am getting "buffer overflow detected" in the log.
> > Here are the contents of the log from both SQL and pcp commands:
> >
> > 1)
> > sudo -u postgres pcp_pool_status -w -v -h localhost -p 9898 -U postgres
> >
> > 2025-11-27 13:30:19.298 [4486]: [3-1] user=3D[No Connection],db=3D[No
> > Connection],app=3Dpcp_main LOG:  forked new pcp worker, pid=3D4495
> > socket=3D7
> > 2025-11-27 13:30:19.298 [4486]: [4-1] user=3D[No Connection],db=3D[No
> > Connection],app=3Dpcp_main LOCATION:  pcp_child.c:327
> > *** buffer overflow detected ***: terminated
> > 2025-11-27 13:30:20.315 [4486]: [5-1] user=3D[No Connection],db=3D[No
> > Connection],app=3Dpcp_main LOG:  PCP process with pid: 4495 exits with
> > status 134 by signal 6
> > 2025-11-27 13:30:20.315 [4486]: [6-1] user=3D[No Connection],db=3D[No
> > Connection],app=3Dpcp_main LOCATION:  pcp_child.c:394
> >
> > 2)
> > sudo -u postgres psql -w -h localhost -p 9999 -U postgres -c "SHOW POOL=
_STATUS"
> >
> > 2025-11-27 13:31:34.385 [4390]: [1-1]
> > user=3Dpostgres,db=3Dpostgres,app=3Dpsql LOG:  DB node id: 0 backend pi=
d:
> > 10166 statement: SELECT pg_catalog.version()
> > 2025-11-27 13:31:34.385 [4390]: [2-1]
> > user=3Dpostgres,db=3Dpostgres,app=3Dpsql LOCATION:
> > pool_proto_modules.c:3803
> > *** buffer overflow detected ***: terminated
> >
> >
> >
> > And here is my pgpool.conf file (only changed lines - diff compared to
> > pgpool.conf.sample)
> > diff --unchanged-line-format=3D --old-line-format=3D
> > --new-line-format=3D'%L' pgpool.conf.sample pgpool.conf
> >
> > listen_addresses =3D '*'
> > unix_socket_directories =3D '/var/run/pgpool'
> > pcp_socket_dir =3D '/var/run/pgpool'
> > serialize_accept =3D on
> > backend_hostname0 =3D '192.168.68.104'
> > backend_port0 =3D 5432
> > backend_weight0 =3D 1
> > backend_data_directory0 =3D '/data/pgdata/18'
> > backend_flag0 =3D 'ALWAYS_PRIMARY'
> > backend_application_name0 =3D 'primary'
> > backend_hostname1 =3D '192.168.68.105'
> > backend_port1 =3D 5432
> > backend_weight1 =3D 1
> > backend_data_directory1 =3D '/data/pgdata/18'
> > backend_flag1 =3D 'DISALLOW_TO_FAILOVER'
> > backend_application_name1 =3D 'replica_1'
> > num_init_children =3D 96
> > max_pool =3D 2
> > child_life_time =3D 0
> > log_line_prefix =3D '%m [%p]: [%l-1] user=3D%u,db=3D%d,app=3D%a '   #
> > printf-style string to output at beginning of each log line.
> > log_connections =3D off
> > log_disconnections =3D off
> > log_per_node_statement =3D on
> > log_standby_delay =3D 'always'
> > log_error_verbosity =3D verbose          # terse, default, or verbose m=
essages
> > log_filename =3D 'pgpool-01-%a.log'
> > write_function_list =3D
> > 'currval,lastval,nextval,setval,public.upgrade_.*,upgrade_.*,public.upd=
ate_.*,update_.*,public.selsert_.*,selsert_.*,public.purge_.*,purge_.*,publ=
ic.process_.*,process_.*,public.move_.*,move_.*,public.merge_.*,merge_.*,pu=
blic.mark_.*,mark_.*,billing.can_ahs_claim_charge,billing.can_ahs_apply_.*'
> > statement_level_load_balance =3D on
> > sr_check_period =3D 5s
> > sr_check_user =3D 'pgpool_monitor'
> > delay_threshold_by_time =3D 500ms
> > health_check_period =3D 10
> > health_check_timeout =3D 30
> > health_check_user =3D 'pgpool_monitor'
> > health_check_max_retries =3D 10
> > failover_on_backend_error =3D off
> > check_temp_table =3D trace
> >
> >