[#67346] Future of test suites for Ruby — Charles Oliver Nutter <headius@...>

I'll try to be brief so we can discuss all this. tl;dr: RubySpec is

19 messages 2015/01/05

[ruby-core:67509] [ruby-trunk - Feature #10714] Array#reject! nonlinear performance problem

From: akr@...
Date: 2015-01-11 12:50:27 UTC
List: ruby-core #67509
Issue #10714 has been updated by Akira Tanaka.


I think nobu has a right to accept this feature because the documented bahavior which will be changed was implemented and committed by nobu and others don't requested.

If nobu don't think so, we need approval of matz.

----------------------------------------
Feature #10714: Array#reject! nonlinear performance problem
https://bugs.ruby-lang.org/issues/10714#change-50928

* Author: Akira Tanaka
* Status: Open
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
----------------------------------------
I found Array#reject! is too slow.

I measured it and it seems the performance is nonlinear.

```
% ./ruby -v -e '
20.times {|i|
  a = [nil]*i*10000;
  t1 = Time.now
  a.reject! { true }
  t2 = Time.now
  t = t2 - t1
  p ["*" * (t * 20).to_i , t]
}
'
ruby 2.3.0dev (2015-01-08 trunk 49175) [x86_64-linux]
["", 3.683e-06]
["", 0.019059723]
["*", 0.052964771]
["**", 0.1177318]
["****", 0.208824818]
["******", 0.334757354]
["*********", 0.482717139]
["*************", 0.669606441]
["*****************", 0.866588588]
["**********************", 1.116195389]
["***************************", 1.392828177]
["**********************************", 1.701906753]
["****************************************", 2.013290644]
["************************************************", 2.415258165]
["*******************************************************", 2.783918449]
["*****************************************************************", 3.27417584]
["**************************************************************************", 3.724958298]
["**************************************************************************************", 4.307263787]
["**************************************************************************************************", 4.922179118]
["************************************************************************************************************", 5.403641168]
```

Ruby 2.2, 2.1, 2.0, 1.9.3 also have the problem but Ruby 1.9.2 works well.

```
% ruby-1.9.2-p330 -v -e ' 
20.times {|i|
  a = [nil]*i*10000;
  t1 = Time.now
  a.reject! { true }
  t2 = Time.now
  t = t2 - t1
  p ["*" * (t * 20).to_i , t]
}
'
ruby 1.9.2p330 (2014-08-07 revision 47094) [x86_64-linux]
["", 2.111e-06]
["", 0.000798623]
["", 0.001441408]
["", 0.00155386]
["", 0.001656242]
["", 0.002166389]
["", 0.002355492]
["", 0.002703977]
["", 0.003123692]
["", 0.00348722]
["", 0.003884792]
["", 0.004300034]
["", 0.004701378]
["", 0.006854893]
["", 0.005485207]
["", 0.005972309]
["", 0.006298597]
["", 0.006901775]
["", 0.007216343]
["", 0.007373332]
```




-- 
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