Re: lockup in parallel hash join on dikkop (freebsd 14.0-current)

On 1/28/23 05:53, Andres Freund wrote:
> Hi,
> 
> On 2023-01-27 23:18:39 -0500, Tom Lane wrote:
>> I also saw it on florican, which is/was an i386 machine using clang and
>> pretty standard build options other than
>>     'CFLAGS' => '-msse2 -O2',
>> so I think this isn't too much about machine architecture or compiler
>> flags.
> 
> Ah. Florican dropped of the BF status page and I was too lazy to look
> deeper. You have a penchant for odd architectures, so it didn't seem too crazy
> :)
> 
> 
>> Machine speed might matter though.  elver is a good deal faster than
>> florican was, and dikkop is slower yet.  I gather Thomas has seen this
>> only once on elver, but I saw it maybe a dozen times over a couple of
>> years on florican, and now dikkop has hit it after not so many runs.
> 
> Re-reading the old thread, it is interesting that you tried hard to reproduce
> it outside of the BF, without success:
> https://postgr.es/m/2398828.1646000688%40sss.pgh.pa.us
> 
> Such problems are quite annoying. Last time I hit such a case was
> https://postgr.es/m/20220325052654.3xpbmntatyofau2w%40alap3.anarazel.de
> but I can't see anything like that being the issue here.
> 

FWIW I'll wait for dikkop to finish the current buildfarm run (it's
currently chewing on HEAD) and then will try to do runs of the 'joins'
test in a loop. That's where dikkop got stuck before.

regards

-- 
Tomas Vondra
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