Issue #10714 has been updated by Nobuyoshi Nakada.


Forgot a patch of the tests

~~~diff
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index 31f33dd..33fc5d6 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -661,7 +661,7 @@ class TestArray < Test::Unit::TestCase
 
     bug2545 = '[ruby-core:27366]'
     a = @cls[ 5, 6, 7, 8, 9, 10 ]
-    assert_equal(9, a.delete_if {|i| break i if i > 8; assert_equal(a[0], i) || true if i < 7})
+    assert_equal(9, a.delete_if {|i| break i if i > 8; i < 7})
     assert_equal(@cls[7, 8, 9, 10], a, bug2545)
   end
 
@@ -1160,7 +1160,7 @@ class TestArray < Test::Unit::TestCase
 
     bug2545 = '[ruby-core:27366]'
     a = @cls[ 5, 6, 7, 8, 9, 10 ]
-    assert_equal(9, a.reject! {|i| break i if i > 8; assert_equal(a[0], i) || true if i < 7})
+    assert_equal(9, a.reject! {|i| break i if i > 8; i < 7})
     assert_equal(@cls[7, 8, 9, 10], a, bug2545)
   end
 
~~~

----------------------------------------
Bug #10714: Array#reject! nonlinear performance problem
https://bugs.ruby-lang.org/issues/10714#change-50908

* Author: Akira Tanaka
* Status: Rejected
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.3.0dev (2015-01-08 trunk 49175) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
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]
```




-- 
https://bugs.ruby-lang.org/