<div dir="ltr"><div dir="ltr"><div class="gmail_default" style="font-family:"comic sans ms",sans-serif"></div><div style="font-family:"comic sans ms",sans-serif">Dear Tatsuo,</div><div style="font-family:"comic sans ms",sans-serif"><br></div><div style="font-family:"comic sans ms",sans-serif">Thank you for your continued support.</div><div style="font-family:"comic sans ms",sans-serif"><br></div><div style="font-family:"comic sans ms",sans-serif">I have attached the trace file and the pgpool .log for your review. I don't see the semaphore error within the log itself. Could you please clarify how to identify if pgpool failed to acquire the semaphore at startup? Additionally, could you provide guidance on how to resolve this issue if it has occurred?</div><div style="font-family:"comic sans ms",sans-serif"><br></div><div style="font-family:"comic sans ms",sans-serif">Best Regards,</div><div style="font-family:"comic sans ms",sans-serif">Maria </div><div style="font-family:"comic sans ms",sans-serif"><br></div><input name="virtru-metadata" type="hidden" value="{"email-policy":{"disableCopyPaste":false,"disablePrint":false,"disableForwarding":false,"enableNoauth":false,"expandedWatermarking":false,"expires":false,"sms":false,"expirationNum":1,"expirationUnit":"days","isManaged":false,"persistentProtection":false},"attachments":{},"compose-id":"1","compose-window":{"secure":false}}"></div><br><div class="gmail_quote gmail_quote_container" style=""><div dir="ltr" class="gmail_attr">On Wed, Feb 12, 2025 at 9:20 PM Tatsuo Ishii <<a href="mailto:ishii@postgresql.org">ishii@postgresql.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">[Cc:ed to pgpoo-general]<br>
<br>
Hello Maria,<br>
<br>
Please Cc: to pgpool-general so that our community can share valuable<br>
info.<br>
<br>
> Hello Tatsuo,<br>
> <br>
> This is how we installed pgpool.<br>
> <br>
> mkdir -p /local/opt/points/pgpool/4.4.6<br>
> cd /usr/src<br>
> wget <a href="https://protect2.fireeye.com/v1/url?k=31323334-501d2dca-3131568e-454455534531-6acd631f770dce77&q=1&e=50e5f7b9-15c6-4965-86ea-096504160ff4&u=https%3A%2F%2Fwww.pgpool.net%2Fmediawiki%2Fimages%2Fpgpool-II-4.4.6.tar.gz" rel="noreferrer" target="_blank">https://protect2.fireeye.com/v1/url?k=31323334-501d2dca-3131568e-454455534531-6acd631f770dce77&q=1&e=50e5f7b9-15c6-4965-86ea-096504160ff4&u=https%3A%2F%2Fwww.pgpool.net%2Fmediawiki%2Fimages%2Fpgpool-II-4.4.6.tar.gz</a><br>
> tar -xvzf pgpool-II-4.4.6.tar.gz<br>
> cd pgpool-II-4.4.6/<br>
> ./configure --prefix=/local/opt/points/pgpool/4.4.6 --enable-sequence-lock<br>
> --with-openssl<br>
> make ; make install<br>
> <br>
> Are we missing something?<br>
<br>
No, except --enable-sequence-lock is not necessary if you run pgpool<br>
with streaming replication mode.<br>
<br>
BTW, I suspect the source of the problem is, pgpool failed to acquire<br>
semaphore at the startup for some reasons. To confirm the theory (and<br>
possibly to know the cause), can you run pgpool with strace and share<br>
the output? For example:<br>
<br>
strace -f --trace=ipc pgpool [options....]<br>
<br>
If you succeed, you will see something like:<br>
<br>
semget(IPC_PRIVATE, 8, IPC_CREAT|IPC_EXCL|0600) = 655401<br>
semctl(655401, 0, SETVAL, 0x7ffe00000001) = 0<br>
semctl(655401, 1, SETVAL, 0x7ffe00000001) = 0<br>
semctl(655401, 2, SETVAL, 0x7ffe00000001) = 0<br>
semctl(655401, 3, SETVAL, 0x7ffe00000001) = 0<br>
semctl(655401, 4, SETVAL, 0x7ffe00000001) = 0<br>
semctl(655401, 5, SETVAL, 0x7ffe00000001) = 0<br>
semctl(655401, 6, SETVAL, 0x7ffe00000001) = 0<br>
semctl(655401, 7, SETVAL, 0x7ffe00000001) = 0<br>
<br>
> On Wed, Feb 12, 2025 at 10:23 AM Maria Nieva <<a href="mailto:maria.nieva@points.com" target="_blank">maria.nieva@points.com</a>> wrote:<br>
> <br>
>><br>
>> Dear Tatsuo,<br>
>><br>
>> Thank you for your response.<br>
>><br>
>> I've attached the pgpool log from our production environment during the<br>
>> upgrade. The semaphore warning shows right away. We have since rolled<br>
>> back to version 4.1.1. I've also included the config file for your<br>
>> reference.<br>
>><br>
>> Please let me know if you have any further questions.<br>
>><br>
>><br>
>> Best Regards,<br>
>> Maria<br>
>><br>
>><br>
>><br>
>><br>
>> On Tue, Feb 11, 2025 at 7:40 PM Tatsuo Ishii <<a href="mailto:ishii@postgresql.org" target="_blank">ishii@postgresql.org</a>> wrote:<br>
>><br>
>>> [Cc:ed to pgpool-general]<br>
>>><br>
>>> Thank you for the log. There's no semaphore errors. Now I need to know<br>
>>> how you installed 4.4.6. If from RPM, did you use Pgpool-II community<br>
>>> version?<br>
>>><br>
>>> <a href="https://protect2.fireeye.com/v1/url?k=31323334-501d2dca-3131568e-454455534531-ba8a251b4f567a67&q=1&e=e45aec18-0dee-41a2-bde7-d39d532f71f2&u=https%3A%2F%2Fpgpool.net%2Fmediawiki%2Findex.php%2FYum_Repository" rel="noreferrer" target="_blank">https://protect2.fireeye.com/v1/url?k=31323334-501d2dca-3131568e-454455534531-ba8a251b4f567a67&q=1&e=e45aec18-0dee-41a2-bde7-d39d532f71f2&u=https%3A%2F%2Fpgpool.net%2Fmediawiki%2Findex.php%2FYum_Repository</a><br>
>>><br>
>>> Can you share pgpool.conf? (please mask sensitive information such as<br>
>>> password or IP).<br>
>>><br>
>>> Best reagards,<br>
>>> --<br>
>>> Tatsuo Ishii<br>
>>> SRA OSS K.K.<br>
>>> English:<br>
>>> <a href="https://protect2.fireeye.com/v1/url?k=31323334-501d2dca-3131568e-454455534531-bbb96eab86ee7dab&q=1&e=e45aec18-0dee-41a2-bde7-d39d532f71f2&u=http%3A%2F%2Fwww.sraoss.co.jp%2Findex_en%2F" rel="noreferrer" target="_blank">https://protect2.fireeye.com/v1/url?k=31323334-501d2dca-3131568e-454455534531-bbb96eab86ee7dab&q=1&e=e45aec18-0dee-41a2-bde7-d39d532f71f2&u=http%3A%2F%2Fwww.sraoss.co.jp%2Findex_en%2F</a><br>
>>> Japanese:<a href="http://www.sraoss.co.jp" rel="noreferrer" target="_blank">http://www.sraoss.co.jp</a><br>
>>><br>
>>><br>
>>> > Dear Tatsuo,<br>
>>> ><br>
>>> > Thank you for your prompt response. I have attached our pgpool log for<br>
>>> your<br>
>>> > review.<br>
>>> ><br>
>>> > Please advise on how to resolve the semaphore error. Your guidance is<br>
>>> > greatly appreciated.<br>
>>> ><br>
>>> ><br>
>>> ><br>
>>> ><br>
>>> > On Mon, Feb 10, 2025 at 7:09 PM Tatsuo Ishii <<a href="mailto:ishii@postgresql.org" target="_blank">ishii@postgresql.org</a>><br>
>>> wrote:<br>
>>> ><br>
>>> >> > Hello,<br>
>>> >> ><br>
>>> >> > We recently upgraded pgpool from 4.1.1 to 4.4.6. We noticed that we<br>
>>> are<br>
>>> >> > getting this<br>
>>> >> ><br>
>>> >> > 2025-02-08 01:39:33.724 PROCESS: WORKER DB: [No Connection] USER: [No<br>
>>> >> > Connection] APPL: sr_check_worker % WARNING: failed to lock<br>
>>> semaphore<br>
>>> >> [snip]<br>
>>> >> > Connection] APPL: sr_check_worker % LOCATION: pool_sema.c:202<br>
>>> >> ><br>
>>> >> > This doesn't show much<br>
>>> >> ><br>
>>> >> > ipcs -s<br>
>>> >> ><br>
>>> >> > ------ Semaphore Arrays --------<br>
>>> >> > key semid owner perms nsems<br>
>>> >><br>
>>> >> Strange. In your case you should see something like:<br>
>>> >><br>
>>> >> ------ Semaphore Arrays --------<br>
>>> >> key semid owner perms nsems<br>
>>> >> 0x00000000 655386 t-ishii 600 8<br>
>>> >><br>
>>> >> ("t-ishii" is the user name of the user who started pgpool)<br>
>>> >><br>
>>> >> > This is in our *pgpool.conf *<br>
>>> >> > backend_clustering_mode = 'streaming_replication'<br>
>>> >> > num_init_children = 250<br>
>>> >> > min_spare_children = 25<br>
>>> >> > max_spare_children = 50<br>
>>> >> > max_pool = 2<br>
>>> >> > child_life_time = 300<br>
>>> >> > child_max_connections = 2<br>
>>> >> > connection_life_time = 300<br>
>>> >> > client_idle_limit = 300<br>
>>> >> ><br>
>>> >> > Can you please help us understand why we see the warning? What is it?<br>
>>> >><br>
>>> >> Pgpool worker process complains that it cannot aquire a semaphore.<br>
>>> >><br>
>>> >> > How<br>
>>> >> > do we resolve this?<br>
>>> >><br>
>>> >> To resolve the problem, we need the pgpool log at the start up because<br>
>>> >> the semaphore is configured at that time.<br>
>>> >><br>
>>> >> Best reagards,<br>
>>> >> --<br>
>>> >> Tatsuo Ishii<br>
>>> >> SRA OSS K.K.<br>
>>> >> English:<br>
>>> >><br>
>>> <a href="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" rel="noreferrer" target="_blank">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</a><br>
>>> >> Japanese:<a href="http://www.sraoss.co.jp" rel="noreferrer" target="_blank">http://www.sraoss.co.jp</a><br>
>>> >><br>
>>><br>
>><br>
</blockquote></div></div>