Re: Align memory context level numbering in pg_log_backend_memory_contexts()

On Thu, 17 Apr 2025 at 02:20, torikoshia <torikoshia@oss.nttdata.com> wrote:
> Regarding the implementation:
> In the initial patch attached, I naïvely incremented the level just
> before emitting the log line.
> However, it might be cleaner to simply initialize the level variable to
> 1 from the start. This could help avoid unnecessary confusion when
> debugging that part of the code.

I didn't look at your patch before, but have now and agree that's not
the best way.

> Similarly, I noticed that in pg_get_process_memory_contexts(), the level
> is initialized to 0 in ProcessGetMemoryContextInterrupt(void):
>
>      int level = 0;
>      ..
>      MemoryContextStatsInternal(c, level, 100, 100, &grand_totals, ..
>
> If we want to be consistent, perhaps it would make sense to start from 1
> there as well.

Yes.

> BTW level variable has existed since before pg_backend_memory_contexts
> was introduced — it was originally used for functions that help inspect
> memory contexts via the debugger. Because of that, I think changing this
> would affect not only these functions codes but some older ones.

I get the impression that it wasn't well thought through prior to
this. If you asked for max_level of 10 it would stop at 9. Changing
these to 1-based levels means we'll now stop at level 10 without
printing any more levels than we did before.

The attached patch is how I think we should do it.

David