Re: [COMMITTERS] pgsql: Replication lag tracking for walsenders

On Sat, Apr 22, 2017 at 9:04 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
>> Simon Riggs wrote:
>>> Replication lag tracking for walsenders
>>>
>>> Adds write_lag, flush_lag and replay_lag cols to pg_stat_replication.
>
>> Did anyone notice that this seems to be causing buildfarm member 'tern'
>> to fail the recovery check? See here:
>
>> https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=tern&dt=2017-04-21%2012%3A48%3A09&stg=recovery-check
>> which has
>> TRAP: FailedAssertion("!(lsn >= prev.lsn)", File: "walsender.c", Line: 3331)
>
>> Line 3331 was added by this commit.
>
> Note that while that commit was some time back, tern has only just started
> running recovery-check, following its update to the latest buildfarm
> script. It looks like it's run that test four times and failed twice,
> so far. So, not 100% reproducible, but there's something rotten there.
> Timing-dependent, maybe?

Thanks. I'm away from my computer right now but will investigate this
and send a fix later today.

--
Thomas Munro
http://www.enterprisedb.com