Re: gawk -i inplace is an order of magnitude faster when also redirecting stdout

[Ed Morton]

Arnold - sounds good but could you change this statement:

   Due to this implementation, it helps to..

to:

   Due to this implementation, it improves execution speed to...

just so it's clear to people who don't know about the different types of 
buffering and their implications what difference adding `> /dev/null` 
would make?

Thanks,

    Ed.

On 3/3/2024 12:49 PM, arnold@skeeve.com wrote:
> arnold@skeeve.com  wrote:
>
> > Adding a setvbuf() call didn't work.
> >
> > Using freopen() instead of playing games with the file descriptor
> > might work, but it's also a hassle.
> >
> > Andy - can you look at this? Try: in inplace_begin
> > - dup stdout to a new fd and save it as now
> > - do freopen on stdout to the file. this should set block buffering
> >
> > In inplace_end, do freopen of /dev/fd/NNN where NNN is the duped
> > fd from the original stdout.
> >
> > Thanks,
> >
> > Arnold
> I spent a bunch of time on this and could not make anything
> work. So I'm going with a documentation patch.
>
> Arnold
> ----------------------
> diff --git a/doc/gawk.texi b/doc/gawk.texi
> index a093cb08..769c82c5 100644
> --- a/doc/gawk.texi
> +++ b/doc/gawk.texi
> @@ -39495,6 +39495,11 @@ For each regular file that is processed, the extension 
> redirects
>   standard output to a temporary file configured to have the same owner
>   and permissions as the original.  After the file has been processed,
>   the extension restores standard output to its original destination.
> +(Due to this implementation, it helps to redirect @command{gawk}'s
> +standard output to @file{/dev/null}, instead of leaving it set to
> +your terminal, so that output will be block-buffered instead of
> +line-buffered.)
> +
>   If @code{inplace::suffix} is not an empty string, the original file is
>   linked to a backup @value{FN} created by appending that suffix.  Finally,
>   the temporary file is renamed to the original @value{FN}.