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

On Wed, May 19, 2010 at 8:49 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
> On Wed, 2010-05-19 at 08:21 -0400, Tom Lane wrote:
>> Robert Haas <robertmhaas@gmail.com> writes:
>> > On Wed, May 19, 2010 at 1:47 AM, Fujii Masao <masao.fujii@gmail.com> wrote:
>> >> Yes, but I prefer XLogCtl->SharedRecoveryInProgress, which is the almost
>> >> same indicator as the boolean you suggested. Thought?
>>
>> > It feels cleaner and simpler to me to use the information that the
>> > postmaster already collects rather than having it take locks and check
>> > shared memory, but I might be wrong.  Why do you prefer doing it that
>> > way?
>>
>> The postmaster must absolutely not take locks (once there are competing
>> processes).  This is non negotiable from a system robustness standpoint.
>
> Masao has not proposed this, in fact his proposal was to deliberately
> avoid do so.
>
> I proposed using the state recorded in xlog.c rather than attempting to
> duplicate that with a second boolean in postmaster because that seems
> likely to be more buggy.

Well then how are we reading XLogCtl?

--
Robert Haas
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