Re: Idea for improving buildfarm robustness

On 09/29/2015 12:18 PM, Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>> On 09/29/2015 02:48 PM, Tom Lane wrote:
>>> Also, perhaps we'd only enable this behavior in --enable-cassert builds,
>>> to avoid any risk of a postmaster incorrectly choosing to suicide in a
>>> production scenario.  Or maybe that's overly conservative.
> 
>> Not every buildfarm member uses cassert, so I'm not sure that's the best 
>> way to go. axolotl doesn't, and it's one of those that regularly has 
>> speed problems. Maybe a not-very-well-publicized GUC, or an environment 
>> setting? Or maybe just enable this anyway. If the data directory is gone 
>> what's the point in keeping the postmaster around? Shutting it down 
>> doesn't seem likely to cause any damage.
> 
> The only argument I can see against just turning it on all the time is
> the possibility of false positives.  I mentioned ENFILE and EPERM as
> foreseeable false-positive conditions, and I'm worried that there might be
> others.  It might be good if we have a small list of specific errnos that
> cause us to conclude we should die, rather than a small list that cause us
> not to.  But as long as we're reasonably confident that we're seeing an
> error that means somebody deleted pg_control, I think abandoning ship
> is just fine.

Give me source with the change, and I'll put it on a cheap, low-bandwith
AWS instance and hammer the heck out of it.  That should raise any false
positives we can expect.

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com