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Groups > linux.debian.bugs.dist > #771463
| From | Niko Tyni <ntyni@debian.org> |
|---|---|
| Newsgroups | linux.debian.bugs.dist |
| Subject | Bug#839600: perl: concatenating string instead of sprintf takes all computation power of server |
| Date | 2016-10-03 21:30 +0200 |
| Message-ID | <soh62-z2-61@gated-at.bofh.it> (permalink) |
| References | <snShj-11m-31@gated-at.bofh.it> <snUVQ-2Gn-7@gated-at.bofh.it> <snVRT-3e4-7@gated-at.bofh.it> <snWbf-3zE-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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On Sun, Oct 02, 2016 at 11:59:12PM +0300, Niko Tyni wrote:
> It seems to have to do with the size of the input file rather
> than its contents, but I'm not quite sure yet.
It looks like none of the gory regexps are necessary to trigger it.
Here's a short test case, resulting here in
Rate concat assign sprintf
concat 2928/s -- -94% -94%
assign 47733/s 1530% -- -0%
sprintf 47733/s 1530% 0% --
so showing the 'concat' option has pathologic performance.
It goes away if the length of the base string $s is varied
even slightly, and seems to reappear in 8-byte increments
or decrements. Some of those, like 2**16 - 3, also blow
up the 'sprintf' performance.
The results don't vary much between jessie (Perl 5.20) and sid (5.24)
for me on amd64.
I'll test/bisect this on upstream code next and try to find out if it's
really copy-on-write related or something else.
--
Niko Tyni ntyni@debian.org
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Bug#839600: perl: concatenating string instead of sprintf takes all computation power of server Leszek Dubiel <leszek.dubiel@dubielvitrum.pl> - 2016-10-02 19:00 +0200
Bug#839600: perl: concatenating string instead of sprintf takes all computation power of server Niko Tyni <ntyni@debian.org> - 2016-10-02 21:50 +0200
Bug#839600: perl: concatenating string instead of sprintf takes all computation power of server gregor herrmann <gregoa@debian.org> - 2016-10-02 22:50 +0200
Bug#839600: perl: concatenating string instead of sprintf takes all computation power of server Niko Tyni <ntyni@debian.org> - 2016-10-02 23:10 +0200
Bug#839600: perl: concatenating string instead of sprintf takes all computation power of server gregor herrmann <gregoa@debian.org> - 2016-10-02 23:20 +0200
Bug#839600: perl: concatenating string instead of sprintf takes all computation power of server Niko Tyni <ntyni@debian.org> - 2016-10-03 21:30 +0200
Bug#839600: perl: concatenating string instead of sprintf takes all computation power of server Niko Tyni <ntyni@debian.org> - 2016-10-03 22:30 +0200
Bug#839600: perl: concatenating string instead of sprintf takes all computation power of server Leszek Dubiel <leszek.dubiel@dubielvitrum.pl> - 2016-10-02 23:30 +0200
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