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GeezerVison is showing github.com — Add benchmark for Array#new vs. Fixnum#times + map by Drenmi · Pull Request #91 · fastruby/fast-ruby

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@Drenmi

@Drenmi Drenmi commented Jan 11, 2016

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When you need to map the result of a block invoked a fixed amount of times, you have an option between:

Array.new(n) { ... }

and:

n.times.map { ... }

The latter one is about 60% slower for n = 10, which goes down to around 40% for n > 1_000.

Note: logarithmic scale!

screen shot 2016-01-11 at 20 23 40

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@Drenmi
Add benchmark for Array#new vs. Fixnum#times + map
9be00e7 
When you need to map the result of a block invoked a fixed amount
of times, you have an option between:

```
Array.new(n) { ... }
```

and:

```
n.times.map { ... }
```

The latter one is about 60% slower.
nateberkopec
nateberkopec reviewed Jan 11, 2016
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Comment thread code/array/array-new-vs-fixnum-times-map.rb

@nateberkopec nateberkopec Jan 11, 2016

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How does this change with the number of elements?

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@Drenmi Drenmi Jan 11, 2016

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@nateberkopec: It tapers off a bit, and stabilizes around 40% slower at 1_000 elements and up. Note: logarithmic scale!

screen shot 2016-01-11 at 20 23 40

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@nateberkopec nateberkopec Jan 11, 2016

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Thank you so much for the graph! I'm just getting started with this repo, so someone else should comment, but whenever there's an Array or Enumerable benchmark I'm always curious with how it scales with # of elements. You may want to add a comment explaining that this behaves pretty much the same way at 1 million elements as it does at 10.

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@Drenmi Drenmi Jan 11, 2016

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No problems @nateberkopec. :-) Is a comment in the PR sufficient, or do you want me to add it to the README?

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@nateberkopec nateberkopec Jan 11, 2016

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shrug let's see what someone else thinks

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@deniskorobicyn deniskorobicyn Jan 11, 2016

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I vote for link to this PR in README.md.
This'll make info available for everyone, not only for people who reviewing PR's. Also, link will share that cool graph you have here:)

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@JuanitoFatas JuanitoFatas Jan 11, 2016

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I vote for link to this PR in README.md.

👍

@Drenmi Awesome graph 👏 👏 👏

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@Drenmi Drenmi Jan 12, 2016

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@nateberkopec, @deniskorobicyn, @JuanitoFatas: Thanks for the kind words. 😃 I added the graph to the PR description, and linked to the PR from the README.

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@Drenmi
Add link to benchmark PR in README
bdfed07 
As suggested by @deniskorobicyn, adding a link from the `README.md`
to the PR, which has more information on performance characteristics.
@Drenmi
Drenmi force-pushed the array-new-vs-fixnum-times-map branch from c778665 to bdfed07 Compare January 12, 2016 04:05
@Arcovion

Arcovion commented Jan 12, 2016

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There's a faster way:

require 'benchmark/ips'

LIMIT = 9

def fastest
  [].fill(0, LIMIT, &:itself)
end

def fast
  Array.new(LIMIT, &:itself)
end

def slow
  (0...LIMIT).map(&:itself)
end

def slowest
  LIMIT.times.map(&:itself)
end

Benchmark.ips do |bm|
  bm.report('Array#fill') { fastest }
  bm.report('Array#new') { fast }
  bm.report('Range#map') { slow }
  bm.report('Fixnum#times') { slowest }
  bm.compare!
end
Calculating -------------------------------------
          Array#fill    81.773k i/100ms
           Array#new    72.230k i/100ms
           Range#map    60.548k i/100ms
        Fixnum#times    56.625k i/100ms
-------------------------------------------------
          Array#fill      1.507M (± 1.4%) i/s -      7.605M
           Array#new      1.191M (± 1.7%) i/s -      5.995M
           Range#map    992.912k (± 1.9%) i/s -      4.965M
        Fixnum#times    868.483k (± 0.9%) i/s -      4.360M

Comparison:
          Array#fill:  1506707.9 i/s
           Array#new:  1191006.1 i/s - 1.27x slower
           Range#map:   992912.3 i/s - 1.52x slower
        Fixnum#times:   868483.2 i/s - 1.73x slower
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@avellable

avellable commented Sep 23, 2016

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Let me add a reference to this.

@JuanitoFatas We can merge this.
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@Drenmi

Drenmi commented Jan 8, 2017

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Ping @JuanitoFatas. 😘
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@ixti

ixti commented Jan 13, 2017

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@Drenmi can you please add what @Arcovion said?
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@kindoflew
kindoflew merged commit 1b4a509 into fastruby:master Apr 25, 2022
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8 participants

@Drenmi @Arcovion @avellable @ixti @nateberkopec @JuanitoFatas @deniskorobicyn @kindoflew
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