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change #9754: 5 x slowdown for perl -d

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From:
Jarkko Hietaniemi
Date:
January 19, 2003 09:05
Subject:
change #9754: 5 x slowdown for perl -d
Message ID:
20030119164229.GH450403@lyta.hut.fi
Regarding the bug #20218 "perl -d now an order of magnitude slower
5.6.0 -> 5.8.0" (http://rt.perl.org/rt2/Ticket/Display.html?id=20218)
I now found out that the change #9754

[  9754] By: jhi                                   on 2001/04/19  11:56:07
        Log: Subject: PATCH: Propagate low byte of hints in cop.op_private
             From: Robin Houston <robin@kitsite.com>
             Date: Wed, 18 Apr 2001 17:58:33 +0100
             Message-ID: <20010418175833.B8976@puffinry.freeserve.co.uk>
     Branch: perl
           ! ext/B/B/Deparse.pm op.c

is the one that caused the major speed bump between 5.7.1 and 5.7.2:

5.6.0        :  0.58 0.03
5.6.1        :  0.58 0.03
5.7.0        :  0.58 0.05
5.7.1    9670:  0.62 0.05
         9718:  0.61 0.05
         9742:  0.63 0.05
         9752:  0.64 0.05
         9754:  3.39 0.05
         9762:  3.42 0.05
         9885:  3.43 0.05
        10105:  3.43 0.05
        10517:  3.36 0.04
5.7.2   11355:  3.20 0.05
5.7.3   15039:  4.58 0.05
5.8.0   17638:  4.02 0.07
blead        :  4.07 0.08

The times are user + system seconds, the test script is the eventlog.pl
from the perlbug thread, the input is the first 1000 lines of the 'xaa',
the test command is:

time PERLDB_OPTS=noTTY ./perl -Ilib -d eventpos.pl xab> /dev/null 2>/dev/null

Removing the #9754 from the 5.8.0 restores the reasonable -d times
(there's still some slowdown introduced between 5.7.2 and 5.7.3 that
needs to be found), but (unsurprisingly) breaks the ext/B/t/deparse.t
test, the hints are not deparsed correctly.  But the deparse is not
the only one: also some of the locale pragma tests start failing.

Failed Test          Stat Wstat Total Fail  Failed  List of Failed
-------------------------------------------------------------------------------
../ext/B/t/deparse.t               17   14  82.35%  2-14 16
../lib/locale.t                   117   16  13.68%  2-9 15 54 105-106 108-109
                                                    113 115
46 tests and 268 subtests skipped.
Failed 2/712 test scripts, 99.72% okay. 30/68220 subtests failed, 99.96% okay.

-- 
Jarkko Hietaniemi <jhi@iki.fi> http://www.iki.fi/jhi/ "There is this special
biologist word we use for 'stable'.  It is 'dead'." -- Jack Cohen

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