Re: Re: [COMMITTERS] pgsql: Checkpointer starts before bgwriter to avoid missing fsync reque

On 1 June 2012 14:59, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>> On 1 June 2012 14:29, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> Surely that commit is useless.  Fsync requests go into a queue in shared
>>> memory, which had better have been set up by the postmaster.  There is
>>> no requirement that the receiving process exist before somebody can put
>>> a request into the queue.  If the queue overflows, the requestor has to
>>> take care of the fsync itself, but that is independent of whether the
>>> checkpointer is running yet.
>
>> The problem I saw was about fsync queue message overflow, not actually
>> missing fsyncs, so perhaps I worded the commit message poorly.
>
> Ah.  Well, as long as the overflowed fsyncs do get handled on the
> requesting side, I see no bug here.  No objection to changing the order
> in which we launch the processes, but as Heikki says, it's not clear
> that that is really going to make much difference.

If I see those messages again, I guess you'll be right.

If that happens I suggest just adding a short wait at bgwriter startup.

--
 Simon Riggs                   http://www.2ndQuadrant.com/
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