From: Louis-Philippe <default@...>
Date: 2009-02-21T08:02:56+09:00
Subject: Re: while vs loop

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mmm, Interesting to see loop being this high in the list,
but even if they all loop from 0  to X doesn't mean they can all compared...
I'm not sure what was the initial question (!!!), but mine is about infinite
loop implementations,
where list iterators  of the .each flavour don't do.

So *THE* fastest ruby infinite loop is 'while 1'?



2009/2/20 Ryan Davis <ryand-ruby@zenspider.com>

>
> On Feb 20, 2009, at 13:57 , Louis-Philippe wrote:
>
>  Hi,I saw this thread from last week: while vs loop,
>>
>> I don't think anybody mentioned the slight performance difference between
>> the two,
>>
>
> If you're going to talk performance differences between while and loop,
> don't forget for and each:
>
>  % ./x.rb 1000000
>> # of iterations = 1000000
>>                          user     system      total        real
>> each                  0.150000   0.000000   0.150000 (  0.148313)
>> for                   0.170000   0.000000   0.170000 (  0.173150)
>> each-var              0.230000   0.000000   0.230000 (  0.237410)
>> while                 0.640000   0.010000   0.650000 (  0.644029)
>> loop                  0.780000   0.000000   0.780000 (  0.785485)
>> % ./x.rb 10000000
>> # of iterations = 10000000
>>                          user     system      total        real
>> each                  1.370000   0.010000   1.380000 (  1.380012)
>> for                   1.630000   0.000000   1.630000 (  1.652562)
>> each-var              2.450000   0.010000   2.460000 (  2.479478)
>> while                 5.510000   0.010000   5.520000 (  5.532909)
>> loop                  7.730000   0.020000   7.750000 (  7.786959)
>>
>
>
> require 'benchmark'
>
> max = (ARGV.shift || 1_000_000).to_i
>
> puts "# of iterations = #{max}"
> Benchmark::bm(20) do |x|
>  x.report("each") do
>    (0..max).each do
>    end
>  end
>
>  x.report("for") do
>    for i in 0..max do
>      # do nothing
>    end
>  end
>
>  x.report("each-var") do
>    (0..max).each do |i|
>    end
>  end
>
>  x.report("while") do
>    n = 0
>    while true do
>      break if n >= max
>      n += 1
>    end
>  end
>
>  x.report("loop") do
>    n = 0
>    loop do
>      break if n >= max
>
>      n += 1
>    end
>  end
> end
>
>
>

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