Re: [COMMITTERS] pgsql: Avoid SnapshotResetXmin() during AtEOXact_Snapshot()

On Fri, Mar 24, 2017 at 12:14 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Fri, Mar 24, 2017 at 10:23 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> Avoid SnapshotResetXmin() during AtEOXact_Snapshot()
>>
>> For normal commits and aborts we already reset PgXact->xmin
>> Avoiding touching highly contented shmem improves concurrent
>> performance.
>>
>> Simon Riggs
>
> I'm getting occasional crashes with backtraces that look like this:
>
> #4 0x0000000107e4be2b in AtEOXact_Snapshot (isCommit=<value
> temporarily unavailable, due to optimizations>, isPrepare=0 '\0') at
> snapmgr.c:1154
> #5 0x0000000107a76c06 in CleanupTransaction () at xact.c:2643
>
> I suspect that is the fault of this patch. Please fix or revert.

Also, the entire buildfarm is turning red.

longfin, spurfowl, and magpie all show this assertion failure in the
log. I haven't checked the others.

TRAP: FailedAssertion("!(MyPgXact->xmin == 0)", File: "snapmgr.c", Line: 1154)

--
Robert Haas
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