From: "charliesome (Charlie Somerville)" <charliesome@...>
Date: 2013-12-07T11:07:30+09:00
Subject: [ruby-core:58930] [ruby-trunk - Bug #9221] Time.parse performance	becomes exponentially worse as string length grows


Issue #9221 has been updated by charliesome (Charlie Somerville).


Reproduced on trunk:

irb(main):027:0> RUBY_DESCRIPTION
=> "ruby 2.1.0dev (2013-12-07 trunk 44044) [x86_64-darwin13.0]"
irb(main):028:0> Benchmark.measure { Time.parse("12:00 PM " + "f"*30) }.to_s
=> "  4.760000   0.000000   4.760000 (  4.759983)\n"
irb(main):029:0> Benchmark.measure { Time.parse("12:00 PM " + "f"*31) }.to_s
=> "  7.770000   0.000000   7.770000 (  7.787989)\n"
irb(main):030:0> Benchmark.measure { Time.parse("12:00 PM " + "f"*32) }.to_s
=> " 12.390000   0.000000  12.390000 ( 12.405786)\n"
----------------------------------------
Bug #9221: Time.parse performance becomes exponentially worse as string length grows
https://bugs.ruby-lang.org/issues/9221#change-43479

Author: mpelzsherman (Michael Pelz-Sherman)
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 
ruby -v: ruby-2.0.0-p247
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


See attached script. Output:

parsing 12:00 PM fffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.010443
parsing 12:00 PM ffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.017739
parsing 12:00 PM fffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.028127
parsing 12:00 PM ffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.049885
parsing 12:00 PM fffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.071379
parsing 12:00 PM ffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.112612
parsing 12:00 PM fffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.184517
parsing 12:00 PM ffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.293784
parsing 12:00 PM fffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.476253
parsing 12:00 PM ffffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 0.786087
parsing 12:00 PM fffffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 1.256976
parsing 12:00 PM ffffffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 2.019426
parsing 12:00 PM fffffffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 3.300646
parsing 12:00 PM ffffffffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 5.37757
parsing 12:00 PM fffffffffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 8.763601
parsing 12:00 PM ffffffffffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 14.165842
parsing 12:00 PM fffffffffffffffffffffffffffffffff
2013-12-05 12:00:00 -0500
elapsed: 23.888907
...



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