Re: pg_rewind test race condition..?

On 04/29/2015 06:03 AM, Stephen Frost wrote:
> * Heikki Linnakangas (hlinnaka@iki.fi) wrote:
>> --- a/src/backend/access/transam/xlog.c
>> +++ b/src/backend/access/transam/xlog.c
>> @@ -7173,7 +7173,10 @@ StartupXLOG(void)
>>        * than is appropriate now that we're not in standby mode anymore.
>>        */
>>       if (fast_promoted)
>> +    {
>> +        sleep(5);
>>           RequestCheckpoint(CHECKPOINT_FORCE);
>> +    }
>>   }
>>
>> The simplest fix would be to force a checkpoint in the regression
>> test, before running pg_rewind. It's a bit of a cop out, since you'd
>> still get the same issue when you tried to do the same thing in the
>> real world. It should be rare in practice - you'd not normally run
>> pg_rewind immediately after promoting the standby - but a better
>> error message at least would be nice..
>
> Forcing a checkpoint in the regression tests and then providing a better
> error message sounds reasonable to me.  I agree that it's very unlikely
> to happen in the real world, even when you're bouncing between systems
> for upgrades, etc, you're unlikely to do it fast enough for this issue
> to exhibit itself, and a better error message would help any users who
> manage to run into this (perhaps during their own testing).

I've committed this simple fix for now.
- Heikki