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bug#44754: Extreme performance degradation in GNU grep 3.4 / 3.6
From: |
Norihiro Tanaka |
Subject: |
bug#44754: Extreme performance degradation in GNU grep 3.4 / 3.6 |
Date: |
Mon, 07 Dec 2020 16:37:51 +0900 |
On Sat, 5 Dec 2020 10:06:27 -0800
Jim Meyering <jim@meyering.net> wrote:
> Thank you for that patch. Can you say a little more about the domain
> of the problem?
> I.e., is it specific to invocations with "-w"?
> Can you provide an example that exhibits the performance improvement,
> with timings?
The test case shown by Frank speeds-up about 10x. That is a little
slower than grep 3.3.
Before:
$ env LC_ALL=C time -p src/grep -Fwif <(seq 300000 | tr 0-9 A-J) <<<foo
real 4.91
user 4.41
sys 0.30
After:
$ env LC_ALL=C time -p src/grep -Fwif <(seq 300000 | tr 0-9 A-J) <<<foo
real 0.37
user 0.16
sys 0.01