From: "gregolsen (Innokenty Mikhailov)" <anotheroneman@...>
Date: 2012-04-04T19:41:30+09:00
Subject: [ruby-core:44124] [ruby-trunk - Bug #6183] Enumerator::Lazy performance issue


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

File new_lazy_enumerator.diff added

Here's the new patch attached - problem, mentioned by Yusuke Endoh, fixed - now I'm creating a new copy of enumerator on each lazy method call.
Also I fixed an error for big arrays - forgot to gc_mark procs array.

Thomas, that's the point - current implementation is very simple and hence very inefficient.
It mimics ruby implementations but as soon as we are in the C sources already - we can come up with something more efficient.


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Bug #6183: Enumerator::Lazy performance issue
https://bugs.ruby-lang.org/issues/6183#change-25651

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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