Horton

Re: [Proposal] Add foreign-server health checks infrastructure

Kyotaro Horiguchi <horikyota.ntt@gmail.com>

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From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
To: kuroda.hayato@fujitsu.com
Cc: katsuragiy@oss.nttdata.com, yuzhihong@gmail.com, tgl@sss.pgh.pa.us, vignesh21@gmail.com, pgsql-hackers@lists.postgresql.org, onderkalaci@gmail.com, masao.fujii@oss.nttdata.com, Shinya11.Kato@oss.nttdata.com
Date: 2023-02-09T02:31:49Z
Lists: pgsql-hackers 
At Fri, 27 Jan 2023 06:57:01 +0000, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com> wrote in 
> I found cfbot failure, PSA fixed version.

+       Unlike <xref linkend="libpq-PQstatus"/>, this function checks socket
+       health. This check is performed by polling the socket. This function is
+       currently available only on systems that support the non-standard
+       <symbol>POLLRDHUP</symbol> extension to the <symbol>poll</symbol> system

I find it quite confusing that we have pqSocketCheck and PQconnCheck,
that does almost the same thing.. Since pqSocketCheck is a static
function, we can modify the function as we like.

I still don't understand why we need pqconnCheck_internal separate
from pqSocketPoll(), and PQconnCheck from pqSocketCheck.

https://www.postgresql.org/message-id/flat/TYAPR01MB58665BF23D38EDF10028DE2AF5299%40TYAPR01MB5866.jpnprd01.prod.outlook.com#47d21431bf9fa94f763c824f6e81fa54
> IIUC, pqSocketCheck () calls pqSocketPoll(),
> and in the pqSocketPoll() we poll()'d the POLLIN or POLLOUT event.
> But according to [1], we must wait POLLRDHUP event,
> so we cannot reuse it straightforward.

Yeah, I didn't suggest to use the function as-is. Couldn't we extend
the fucntion by letting it accept end_time = 0 && !forRead &&
!forWrite, not causing side effects?

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center

Commits

  1. postgres_fdw: Extend postgres_fdw_get_connections to return user name.

  2. postgres_fdw: Fix bug in connection status check.

  3. postgres_fdw: Add connection status check to postgres_fdw_get_connections().

  4. postgres_fdw: Add "used_in_xact" column to postgres_fdw_get_connections().

  5. doc: Enhance documentation for postgres_fdw_get_connections() output columns.

  6. Avoid reference to nonexistent array element in ExecInitAgg().

  7. Add WL_SOCKET_CLOSED for socket shutdown events.

  8. postgres_fdw: reestablish new connection if cached one is detected as broken.