Re: [PATCH] Small optimization across postgres (remove strlen duplicate usage)

Em dom., 19 de abr. de 2020 às 16:33, Tomas Vondra <
tomas(dot)vondra(at)2ndquadrant(dot)com> escreveu:

> On Sun, Apr 19, 2020 at 11:24:38AM -0300, Ranier Vilela wrote:
> >Hi,
> >strlen it is one of the low fruits that can be harvested.
> >What is your opinion?
> >
>
> That assumes this actually affects/improves performance, without any
> measurements proving that. Considering large number of the places you
> modified are related to DDL (CreateComment, ChooseIndexColumnNames, ...)
> or stuff that runs only once or infrequently (like the changes in
> PostmasterMain or libpqrcv_get_senderinfo). Likewise, it seems entirely
> pointless to worry about strlen() overhead e.g. in fsync_parent_path
> which is probably dominated by I/O.
>
With code as interconnected as postgres, it is difficult to say that a
function, which calls strlen, repeatedly, would not have any gain.
Regarding the functions, I was just being consistent, trying to remove all
occurrences, even where, there is very little gain.

>
> Maybe there are places where this would help, but I don't see a reason
> to just throw away all strlen calls and replace them with something
> clearly less convenient and possibly more error-prone (I'd expect quite
> a few off-by-one mistakes with this).
>
Yes, always, it is prone to errors, but for the most part, they are safe
changes.
It passes all 199 tests, of course it has not been tested in a real
production environment.
Perhaps the time is not the best, the end of the cycle, but, once done, I
believe it would be a good harvest.

Thank you for comment.

regards,
Ranier Vilela