From: "trans (Thomas Sawyer)" <transfire@...>
Date: 2012-03-21T23:33:23+09:00
Subject: [ruby-core:43536] [ruby-trunk - Bug #6183] Enumerator::Lazy performance issue


Issue #6183 has been updated by trans (Thomas Sawyer).


Granted that seems like a bit too much overhead, but the advantage to lazy is not in a 1-to-1 comparison with non-lazy. Try removing the `.each` call at the end and adding `.take(10)` instead.

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Bug #6183: Enumerator::Lazy performance issue
https://bugs.ruby-lang.org/issues/6183#change-25016

Author: gregolsen (Innokenty Mikhailov)
Status: Open
Priority: Normal
Assignee: 
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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