Re: pgsql: Add parallel-aware hash joins.

On 2017-12-21 08:49:46 +0000, Andres Freund wrote:
> Add parallel-aware hash joins.

There's to relatively mundane failures:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=tern&dt=2017-12-21%2008%3A48%3A12
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=termite&dt=2017-12-21%2008%3A50%3A08

but also one that's a lot more interesting:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=capybara&dt=2017-12-21%2008%3A50%3A08

which shows an assert failure:

#2  0x00000000008687d1 in ExceptionalCondition (conditionName=conditionName@entry=0xa76a98
"!(!accessor->sts->participants[i].writing)",errorType=errorType@entry=0x8b2c49 "FailedAssertion",
fileName=fileName@entry=0xa76991"sharedtuplestore.c", lineNumber=lineNumber@entry=273) at assert.c:54
 
#3  0x000000000089883e in sts_begin_parallel_scan (accessor=0xfaf780) at sharedtuplestore.c:273
#4  0x0000000000634de4 in ExecParallelHashRepartitionRest (hashtable=0xfaec18) at nodeHash.c:1369
#5  ExecParallelHashIncreaseNumBatches (hashtable=0xfaec18) at nodeHash.c:1198
#6  0x000000000063546b in ExecParallelHashTupleAlloc (hashtable=hashtable@entry=0xfaec18, size=40,
shared=shared@entry=0x7ffee26a8868)at nodeHash.c:2778
 
#7  0x00000000006357c8 in ExecParallelHashTableInsert (hashtable=hashtable@entry=0xfaec18, slot=slot@entry=0xfa76f8,
hashvalue=<optimizedout>) at nodeHash.c:1696
 
#8  0x0000000000635b5f in MultiExecParallelHash (node=0xf7ebc8) at nodeHash.c:288
#9  MultiExecHash (node=node@entry=0xf7ebc8) at nodeHash.c:112

which seems to suggest that something in the state machine logic is
borked. ExecParallelHashIncreaseNumBatches() should've ensured that
everyone has called sts_end_write()...

Greetings,

Andres Freund