From: "gregolsen (Innokenty Mikhailov)" <anotheroneman@...>
Date: 2012-05-16T17:15:31+09:00
Subject: [ruby-core:45076] [ruby-trunk - Bug #6183] Enumerator::Lazy performance issue


Issue #6183 has been updated by gregolsen (Innokenty Mikhailov).

File 16_may.diff added
File new_bench.rb added

=begin
Here's an update.
All methods except (({Lazy#cycle})), (({Lazy#zip})) and (({Lazy#flat_map})) are optimized.
Benchmark results shown below.

I was working in ((<this branch|URL:https://github.com/gregolsen/ruby/tree/lazy_enumerator_optimization>)).
Cycle, zip and flat_map are really tough to convert to procs chaining, however they are working fine in this hybrid solution and can be leave as it is.

All tests pass except test_inspect.
If this implementation is acceptable then the next step will be to fix inspect and add more tests to cover different types of chaining:
like chaining of enumerator chained (cycle, zip, flat_map) methods with procs chained optimized methods.

Please, let me know your thoughts.

Thanks.

 ======================Lazy#map
 user     system      total        real
 Trunk             1.420000   0.010000   1.430000 (  1.461111)
 Optimized         0.830000   0.000000   0.830000 (  0.833560)
 ======================Lazy#select
 user     system      total        real
 Trunk             1.270000   0.010000   1.280000 (  1.274074)
 Optimized         0.780000   0.000000   0.780000 (  0.785303)
 ======================Lazy#grep
 user     system      total        real
 Trunk             1.540000   0.010000   1.550000 (  1.552651)
 Optimized         0.780000   0.000000   0.780000 (  0.783526)
 ======================Lazy#take_while
 user     system      total        real
 Trunk             1.260000   0.000000   1.260000 (  1.257465)
 Optimized         0.780000   0.010000   0.790000 (  0.784682)
 ======================Lazy#drop_while
 user     system      total        real
 Trunk             1.030000   0.000000   1.030000 (  1.030987)
 Optimized         0.400000   0.000000   0.400000 (  0.394112)
 ======================Lazy#reject
 user     system      total        real
 Trunk             1.240000   0.000000   1.240000 (  1.243565)
 Optimized         0.780000   0.000000   0.780000 (  0.781825)
 ======================Lazy#drop
 user     system      total        real
 Trunk             4.150000   0.000000   4.150000 (  4.159758)
 Optimized         1.590000   0.000000   1.590000 (  1.598785)
 ======================Lazy#take
 user     system      total        real
 Trunk             0.520000   0.000000   0.520000 (  0.517902)
 Optimized         0.010000   0.000000   0.010000 (  0.003274)
=end

----------------------------------------
Bug #6183: Enumerator::Lazy performance issue
https://bugs.ruby-lang.org/issues/6183#change-26654

Author: gregolsen (Innokenty Mikhailov)
Status: Assigned
Priority: Low
Assignee: nobu (Nobuyoshi Nakada)
Category: 
Target version: 
ruby -v: ruby 2.0.0dev (2012-03-17 trunk 35075) [x86_64-linux]


I benchmarked Enumerator::Lazy and that's what I got:
                 user     system      total        real
Lazy:        0.690000   0.010000   0.700000 (  0.733160)
Normal:      0.160000   0.010000   0.170000 (  0.186695)

It seems like even with 4 chain links and 3000 elements in initial array, Lazy enumerator is almost 4(!) times slower than the normal case.

Instead of performance benefit we've got 4 times performance drawback.

See test file attached.


-- 
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