Horton
Menu

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

Fujii Masao <masao.fujii@gmail.com>

View thread
From: Fujii Masao <masao.fujii@gmail.com>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>, 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: 2010-05-18T06:45:00Z
Lists: pgsql-hackers 
On Tue, May 18, 2010 at 3:24 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
> On Tue, 2010-05-18 at 15:09 +0900, Fujii Masao wrote:
>> On Tue, May 18, 2010 at 2:26 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> > On Tue, 2010-05-18 at 12:02 +0900, Fujii Masao wrote:
>> >> On Mon, May 17, 2010 at 9:01 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> >> >> (1)
>> >> >> Smart or fast shutdown requested in PM_STARTUP state always removes
>> >> >> the backup_label file if it exists. But it might be still required
>> >> >> for subsequent recovery. I changed your patch so that additionally
>> >> >> the postmaster skips deleting the backup_label in that case.
>> >> >
>> >> > Don't like the name NeedBackupLabel seems too specific. That really
>> >> > corresponds to "we were in recovery". We should have a couple of
>> >> > super-states that correspond to am in recovery/am not in recovery so we
>> >> > can drive it from that.
>> >>
>> >> ISTM that we can use XLogCtl->SharedRecoveryInProgress for that.
>> >> Is this OK?
>> >
>> > That can change state at any time. Would that work?
>>
>> Yes. XLogCtl->SharedRecoveryInProgress is set to TRUE only when
>> XLogCtl structure is initialized (i.e., XLOGShmemInit), and it's
>> set to FALSE only at the end of recovery.
>
> You should be using RecoveryInProgress()

Isn't access to a bool variable atomic?

And I think that postmaster should not take any locks since its
deadlock would cause a fatal situation. No?

Regards,

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