Re: Stefan's bug (was: max_standby_delay considered harmful)

Fujii Masao <masao.fujii@gmail.com>

From: Fujii Masao <masao.fujii@gmail.com>

To: Robert Haas <robertmhaas@gmail.com>

Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>, Simon Riggs <simon@2ndquadrant.com>, Andres Freund <andres@anarazel.de>, Florian Pflug <fgp@phlo.org>, Dimitri Fontaine <dfontaine@hi-media.com>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers <pgsql-hackers@postgresql.org>, Bruce Momjian <bruce@momjian.us>, Greg Smith <greg@2ndquadrant.com>, Josh Berkus <josh@agliodbs.com>

Date: 2010-05-18T02:40:20Z

Lists: pgsql-hackers

On Mon, May 17, 2010 at 10:20 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> OK, I think I understand now.  But, the SIGTERM sent by the postmaster
> doesn't kill the recovery process unconditionally.  It will invoke
> StartupProcShutdownHandler(), which will set set shutdown_requested =
> true.  That gets checked by RestoreArchivedFile() and
> HandleStartupProcInterrupts(), and I think that neither of those can
> get invoked until after the control file has been updated.  Do you see
> a way it can happen?

Yeah, the way is:
StartupXLOG() --> ReadCheckpointRecord() --> ReadRecord() -->
XLogPageRead() --> XLogFileReadAnyTLI() --> XLogFileRead() -->
RestoreArchivedFile()

ReadCheckpointRecord() is called before pg_control is updated.


ISTM that walreceiver might be invoked even after shutdown is requested.
We should prevent the postmaster from starting up walreceiver if
Shutdown > NoShutdown?

Regards,

-- 
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center