Re: Avoid overhead with fprintf related functions - Mailing list pgsql-hackers

From Nathan Bossart
Subject Re: Avoid overhead with fprintf related functions
Date
Msg-id 20220909161956.GA2254174@nathanxps13
Whole thread Raw
In response to Avoid overhead with fprintf related functions  (Ranier Vilela <ranier.vf@gmail.com>)
Responses Re: Avoid overhead with fprintf related functions
List pgsql-hackers
On Fri, Sep 09, 2022 at 10:45:37AM -0300, Ranier Vilela wrote:
> Based on work in [1].
> According to https://cplusplus.com/reference/cstdio/fprintf/
> The use of fprintf is related to the need to generate a string based on a
> format, which should be different from "%s".
> Since fprintf has overhead when parsing the "format" parameter, plus all
> the trouble of checking the va_arg parameters.
> I think this is one of the low fruits available and easy to reap.
> By replacing fprintf with its equivalents, fputs and fputc,
> we avoid overhead and increase security [2] and [3].
> 
> The downside is a huge big churm, which unfortunately will occur.
> But, IHMO, I think the advantages are worth it.
> Note that behavior remains the same, since fputs and fputc do not change
> the expected behavior of fprintf.
> 
> A small performance gain is expected, mainly for the client, since there
> are several occurrences in some critical places, such as
> (usr/src/fe_utils/print.c).

I agree with David [0].  But if you can demonstrate a performance gain,
perhaps it's worth considering a subset of these changes in hot paths.

[0] https://postgr.es/m/CAApHDvp2THseLvCc%2BTcYFBC7FKHpHTs1JyYmd2JghtOVhb5WGA%40mail.gmail.com

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com



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