From: duerst via ruby-core <ruby-core@...>
Date: 2023-01-30T02:46:37+00:00
Subject: [ruby-core:112109] [Ruby master Bug#19288] Ractor JSON parsing significantly slower than linear parsing

Issue #19288 has been updated by duerst (Martin D�rst).





Eregon (Benoit Daloze) wrote in #note-7:



> And then of course there is the issue that Ractor is incompatible with most gems/code out there.

> While JSON loading might work, any non-trivial processing after using a gem is unlikely to work well.

> Other Rubies have solved this in a much more efficient, usable and reliable way, by having no GVL.



But don't other Rubies rely on the programmer to know how to program with threads? That's only usable if you're used to programming with threads and avoid the related issues. The idea (where the implementation and many gems may still have to catch up) behind Ractor is that thread-related issues such as data races can be avoided at the level of the programming model.



----------------------------------------

Bug #19288: Ractor JSON parsing significantly slower than linear parsing

https://bugs.ruby-lang.org/issues/19288#change-101546



* Author: maciej.mensfeld (Maciej Mensfeld)

* Status: Open

* Priority: Normal

* ruby -v: ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]

* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

----------------------------------------

a simple benchmark:



```ruby

require 'json'

require 'benchmark'



CONCURRENT = 5

RACTORS = true

ELEMENTS = 100_000



data = CONCURRENT.times.map do

  ELEMENTS.times.map do

    {

      rand => rand,

      rand => rand,

      rand => rand,

      rand => rand

    }.to_json

  end

end



ractors = CONCURRENT.times.map do

  Ractor.new do

    Ractor.receive.each { JSON.parse(_1) }

  end

end



result = Benchmark.measure do

  if RACTORS

    CONCURRENT.times do |i|

      ractors[i].send(data[i], move: false)

    end



    ractors.each(&:take)

  else

    # Linear without any threads

    data.each do |piece|

      piece.each { JSON.parse(_1) }

    end

  end

end



puts result

```



Gives following results on my 8 core machine:



```shell

# without ractors:

  2.731748   0.003993   2.735741 (  2.736349)



# with ractors

12.580452   5.089802  17.670254 (  5.209755)

```

I would expect Ractors not to be two times slower on the CPU intense work.











-- 

https://bugs.ruby-lang.org/

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