[pgpool-general: 9342] Re: WARNING: failed to lock semaphore

[Tatsuo Ishii]

> Hello,
> 
> We recently upgraded pgpool from 4.1.1 to 4.4.6.  We noticed that we are
> getting this
> 
> 2025-02-08 01:39:33.724 PROCESS: WORKER DB: [No Connection] USER: [No
> Connection] APPL: sr_check_worker % WARNING:  failed to lock semaphore
[snip]
> Connection] APPL: sr_check_worker % LOCATION:  pool_sema.c:202
> 
> This doesn't show much
> 
> ipcs -s
> 
> ------ Semaphore Arrays --------
> key        semid      owner      perms      nsems

Strange. In your case you should see something like:

------ Semaphore Arrays --------
key        semid      owner      perms      nsems     
0x00000000 655386     t-ishii    600        8         

("t-ishii" is the user name of the user who started pgpool)

> This is in our *pgpool.conf *
> backend_clustering_mode = 'streaming_replication'
> num_init_children = 250
> min_spare_children = 25
> max_spare_children = 50
> max_pool = 2
> child_life_time = 300
> child_max_connections = 2
> connection_life_time = 300
> client_idle_limit = 300
> 
> Can you please help us understand why we see the warning? What is it?

Pgpool worker process complains that it cannot aquire a semaphore.

> How
> do we resolve this?

To resolve the problem, we need the pgpool log at the start up because
the semaphore is configured at that time.

Best reagards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp