Re: PostgreSQL 10.5 : Strange pg_wal fill-up, solved with the shutdown checkpoint

On 6/11/18 4:58 μ.μ., Tom Lane wrote:
> Achilleas Mantzios <achill(at)matrix(dot)gatewaynet(dot)com> writes:
>> Remember : postgresql checkpointer decided to remove 5000+ files before shutdown. If any conditions were keeping those files afloat should also hold at this point, right.
>> The question is why didn't Postgresql removed them earlier.
> WAL files get removed/recycled after completion of a checkpoint. So
> apparently, checkpoints were not finishing during normal operation,
> but the shutdown checkpoint managed to terminate normally. That
> eliminates a lot of the usual theories about why checkpoints might
> not be succeeding (like a dirty buffer that always fails to be
> written, say as a result of broken permissions on its file).
>
> The only theory that comes to mind is that the checkpointer process
> was stuck somehow, but just "soft" stuck, in a way that allowed the
> postmaster's time-to-shut-down-please signal to unstick it. No,
> I have no idea how that could happen exactly. If it happens again,
> it'd be really interesting to attach to the checkpointer with a
> debugger and collect a stack trace.

Thank you Tom. Should I also re-run configure --enable-debug && make clean install ? Initially PostgreSQL was built without --enable-debug, so currently it does not show source code line numbers in
gdb bt .

>
> regards, tom lane
>

--
Achilleas Mantzios
IT DEV Lead
IT DEPT
Dynacom Tankers Mgmt