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Re: gsub() is very slow in gawk 5.1.0

From: Ed Morton
Subject: Re: gsub() is very slow in gawk 5.1.0
Date: Wed, 14 Jul 2021 18:47:54 -0500
User-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0

On 7/14/2021 5:33 PM, Neil R. Ormos wrote:
Ed Morton wrote:

On an online forum someone asked how to generate
a string of 100,000,000 "x"s.  They had tried
this in a BEGIN section:
    for(i=1;i<=100000000;i++) s = s "x"
and wanted to know if there was a better
approach. Someone suggested:
    s=sprintf("%*s",1000000000,""); gsub(/ /,"x",s)}
which is also what I'd have also suggested, but
upon testing that they found that the
sprintf+gsub approach was slower than the loop
in gawk 5.1.0 and while I couldn't reproduce
that exactly on cygwin, I can confirm that the
sprintf+gsub solution is much slower than I
expected: [...]
I thought the original question was interesting,
so I addressed it on the help-gawk@gnu.org list.

Thanks Neil - I personally wont be looking at anything on help-gawk but if you'd like to respond to the question that prompted the bug report, it's at https://stackoverflow.com/q/68371275/1745001.


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