Re: [HACKERS] Logical replication - TRAP: FailedAssertion in pgstat.c

On 16/04/17 20:41, Andres Freund wrote:
> On 2017-04-16 10:46:21 +0200, Erik Rijkers wrote:
>> On 2017-04-15 04:47, Erik Rijkers wrote:
>>>
>>> 0001-Reserve-global-xmin-for-create-slot-snasphot-export.patch +
>>> 0002-Don-t-use-on-disk-snapshots-for-snapshot-export-in-l.patch+
>>> 0003-Prevent-snapshot-builder-xmin-from-going-backwards.patch  +
>>> 0004-Fix-xl_running_xacts-usage-in-snapshot-builder.patch      +
>>> 0005-Skip-unnecessary-snapshot-builds.patch
>>
>> I am now using these newer patches:
>> https://www.postgresql.org/message-id/30242bc6-eca4-b7bb-670e-8d0458753a8c%402ndquadrant.com
>>
>>> It builds fine, but when I run the old pbench-over-logical-replication
>>> test I get:
>>>
>>> TRAP: FailedAssertion("!(entry->trans == ((void *)0))", File:
>>> "pgstat.c", Line: 828)
>>
>>
>> To get that error:
> 
> I presume this is the fault of
> http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=139eb9673cb84c76f493af7e68301ae204199746
> if you git revert that individual commit, do things work again?
> 
> - Andres
> 

Yeah it is, it needs to be fenced to happen only after commit, which is
not guaranteed at the point of code, we probably need to put the
pgstat_report_stat() inside the if above after the
CommitTransactionCommand() (that will make it report stats for changes
apply did to pg_subscription_rel after next transaction though) or put
it into it's own if that checks if tx was indeed committed (which is bit
ugly).

--  Petr Jelinek                  http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training &
Services