[pgpool-general: 9351] Re: WARNING: failed to lock semaphore

[Tatsuo Ishii]

[Cc:ed to pgpool-general]

Thank you for the log. There's no semaphore errors. Now I need to know
how you installed 4.4.6. If from RPM, did you use Pgpool-II community
version?
https://pgpool.net/mediawiki/index.php/Yum_Repository

Can you share pgpool.conf? (please mask sensitive information such as
password or IP).

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


> Dear Tatsuo,
> 
> Thank you for your prompt response. I have attached our pgpool log for your
> review.
> 
> Please advise on how to resolve the semaphore error. Your guidance is
> greatly appreciated.
> 
> 
> 
> 
> On Mon, Feb 10, 2025 at 7:09 PM Tatsuo Ishii <ishii at postgresql.org> wrote:
> 
>> > 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:
>> https://protect2.fireeye.com/v1/url?k=31323334-501d2dca-3131568e-454455534531-bbb96eab86ee7dab&q=1&e=beae9c64-ec11-4d5c-8783-026e28457a81&u=http%3A%2F%2Fwww.sraoss.co.jp%2Findex_en%2F
>> Japanese:http://www.sraoss.co.jp
>>