Re: error “server process was terminated by signal 11: Segmentation fault” running pg_create_logical_replication_slot using pgoutput plugin

On Wed, 9 Jul 2025 at 11:43, abrahim abrahao <a_abrahao@yahoo.com.br> wrote:
>
> I got error “server process was terminated by signal 11: Segmentation fault” using pg_create_logical_replication_slot
withpgoutput plugin parameter and using test_decoding worked fine, any idea that is wrong? 
>
> Note: I am using docker container and I also updated shm-size from 1024mb to 2g and I am using shared_buffers=1.5GB.
> This is a test server and there is nothing else running. IT is the first time I am working with logical replication.
>
> See details below
>
> postgresql.conf file:
> wal_level = logical
> max_replication_slots = 10
> max_wal_senders = 20
> listen_addresses = '*'
>
>
>
>  psql -U postgres -h postgres -c "SELECT pg_create_logical_replication_slot('support7561_repslot', 'pgoutput');"
> SSL SYSCALL error: EOF detected
> connection to server was lost
>
>
> < 2025-07-08 14:57:08.653 UTC psql postgres postgres 172.18.0.94(53414) SELECT 00000 2025-07-08 14:57:07 UTC 1096
686d31c3.4482025-07-08 14:57:08.653 UTC > LOG:  Initializing CDC decoder 
> < 2025-07-08 14:57:08.653 UTC psql postgres postgres 172.18.0.94(53414) SELECT 00000 2025-07-08 14:57:07 UTC 1096
686d31c3.4482025-07-08 14:57:08.653 UTC > STATEMENT:  SELECT pg_create_logical_replication_slot('support7561_repslot',
'pgoutput');
> < 2025-07-08 14:57:08.821 UTC      00000 2025-07-08 14:55:38 UTC 923 686d316a.39b 2025-07-08 14:57:08.821 UTC > LOG:
serverprocess (PID 1096) was terminated by signal 11: Segmentation fault 
> < 2025-07-08 14:57:08.821 UTC      00000 2025-07-08 14:55:38 UTC 923 686d316a.39b 2025-07-08 14:57:08.821 UTC >
DETAIL: Failed process was running: SELECT pg_create_logical_replication_slot('support7561_repslot', 'pgoutput'); 
> < 2025-07-08 14:57:08.821 UTC      00000 2025-07-08 14:55:38 UTC 923 686d316a.39b 2025-07-08 14:57:08.821 UTC > LOG:
terminatingany other active server processes 
> < 2025-07-08 14:57:08.829 UTC      00000 2025-07-08 14:55:38 UTC 923 686d316a.39b 2025-07-08 14:57:08.829 UTC > LOG:
allserver processes terminated; reinitializing 
> < 2025-07-08 14:57:09.215 UTC      00000 2025-07-08 14:57:09 UTC 1098 686d31c5.44a 2025-07-08 14:57:09.215 UTC > LOG:
database system was interrupted; last known up at 2025-07-08 14:55:39 UTC 
> < 2025-07-08 14:57:10.037 UTC [unknown] postgres postgres 172.18.0.217(33506)  57P03 2025-07-08 14:57:10 UTC 1101
686d31c6.44d2025-07-08 14:57:10.037 UTC > FATAL:  the database system is in recovery mode 
> < 2025-07-08 14:57:10.437 UTC      00000 2025-07-08 14:57:09 UTC 1098 686d31c5.44a 2025-07-08 14:57:10.437 UTC > LOG:
database system was not properly shut down; automatic recovery in progress 
> < 2025-07-08 14:57:10.450 UTC      00000 2025-07-08 14:57:09 UTC 1098 686d31c5.44a 2025-07-08 14:57:10.450 UTC > LOG:
redo starts at 1FB9/C0000A0 
> < 2025-07-08 14:57:10.456 UTC      00000 2025-07-08 14:57:09 UTC 1098 686d31c5.44a 2025-07-08 14:57:10.456 UTC > LOG:
invalid record length at 1FB9/C054DF8: wanted 24, got 0 
> < 2025-07-08 14:57:10.456 UTC      00000 2025-07-08 14:57:09 UTC 1098 686d31c5.44a 2025-07-08 14:57:10.456 UTC > LOG:
redo done at 1FB9/C054DC0 system usage: CPU: user: 0.00 s, system: 0.00 s, elapsed: 0.00 s 
> < 2025-07-08 14:57:10.475 UTC      00000 2025-07-08 14:57:09 UTC 1099 686d31c5.44b 2025-07-08 14:57:10.475 UTC > LOG:
checkpoint starting: end-of-recovery immediate wait 
> < 2025-07-08 14:57:10.501 UTC      00000 2025-07-08 14:57:09 UTC 1099 686d31c5.44b 2025-07-08 14:57:10.501 UTC > LOG:
checkpoint complete: wrote 86 buffers (0.0%); 0 WAL file(s) added, 0 removed, 2 recycled; write=0.010 s, sync=0.007 s,
total=0.028s; sync files=18, longest=0.003 s, average=0.001 s; distance=339 kB, estimate=339 kB 
> < 2025-07-08 14:57:10.510 UTC      00000 2025-07-08 14:55:38 UTC 923 686d316a.39b 2025-07-08 14:57:10.510 UTC > LOG:
databasesystem is ready to accept connections 
>
>
>  psql -U postgres -h postgres -c "SELECT pg_create_logical_replication_slot('support7561_repslot', 'test_decoding');"
>  pg_create_logical_replication_slot
> ------------------------------------
>  (support7561_repslot,1FB9/C081668)
> (1 row)
>
> postgres@support7560_postgres:/var/lib/postgresql/15/main$ psql -U postgres -h postgres -c "SELECT slot_name, plugin,
slot_type,database, active, restart_lsn, confirmed_flush_lsn FROM pg_replication_slots;" 
>       slot_name      |    plugin     | slot_type | database | active | restart_lsn  | confirmed_flush_lsn
> ---------------------+---------------+-----------+----------+--------+--------------+---------------------
>  support7561_repslot | test_decoding | logical   | postgres | f      | 1FB9/C081630 | 1FB9/C081668
>
>
> SHOW shared_buffers;
>  shared_buffers
> ----------------
>  1532512kB
> (1 row)
>
> postgres=# \! uname -a
> Linux support7560_postgres 6.8.0-1030-gcp #32~22.04.1-Ubuntu SMP Tue Apr 29 23:17:09 UTC 2025 x86_64 x86_64 x86_64
GNU/Linux
>
> psql -U postgres -h postgres -c "select version()"
>                                                                version
>
-------------------------------------------------------------------------------------------------------------------------------------
>  PostgreSQL 15.13 (Ubuntu 15.13-1.pgdg24.04+1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 13.3.0-6ubuntu2~24.04)
13.3.0,64-bit 

Hi Abrahim,

Can you also share the stack trace for the crash?
Also can you share the exact steps used to reproduce the issue?

Thanks and Regards,
Shlok Kyal