Re: Cpu usage 100% on slave. s_lock problem.

On Thu, Sep 26, 2013 at 10:14 PM, Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:
> On Thu, Sep 26, 2013 at 6:08 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>> On 2013-08-27 12:17:55 -0500, Merlin Moncure wrote:
>>> On Tue, Aug 27, 2013 at 10:55 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>>> > On 2013-08-27 09:57:38 -0500, Merlin Moncure wrote:
>>> >> + bool
>>> >> + RecoveryMightBeInProgress(void)
>>> >> + {
>>> >> + /*
>>> >> + * We check shared state each time only until we leave recovery mode. We
>>> >> + * can't re-enter recovery, so there's no need to keep checking after the
>>> >> + * shared variable has once been seen false.
>>> >> + */
>>> >> + if (!LocalRecoveryInProgress)
>>> >> + return false;
>>> >> + else
>>> >> + {
>>> >> + /* use volatile pointer to prevent code rearrangement */
>>> >> + volatile XLogCtlData *xlogctl = XLogCtl;
>>> >> +
>>> >> + /* Intentionally query xlogctl without spinlocking! */
>>> >> + LocalRecoveryInProgress = xlogctl->SharedRecoveryInProgress;
>>> >> +
>>> >> + return LocalRecoveryInProgress;
>>> >> + }
>>> >> + }
>>> >
>>> > I don't think it's acceptable to *set* LocalRecoveryInProgress
>>> > here. That should only be done in the normal routine.
>>>
>>> quite right -- that was a major error -- you could bypass the
>>> initialization call to the xlog with some bad luck.
>>
>> I've seen this in profiles since, so I'd appreciate pushing this
>> forward.
>
> roger that -- will push ahead when I get into the office...

attached is new version fixing some comment typos.

merlin