From: "mame (Yusuke Endoh)" <mame@...>
Date: 2012-07-26T21:37:36+09:00
Subject: [ruby-core:46787] [ruby-trunk - Bug #6183] Enumerator::Lazy performance issue


Issue #6183 has been updated by mame (Yusuke Endoh).


Your patch makes the following code stuck.

  p [1,2,3].to_enum.lazy.cycle.take(10).to_a

It should print [1, 2, 3, 1, 2, 3, 1, 2, 3, 1].

-- 
Yusuke Endoh <mame@tsg.ne.jp>
----------------------------------------
Bug #6183: Enumerator::Lazy performance issue
https://bugs.ruby-lang.org/issues/6183#change-28457

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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