From: ko1@... Date: 2021-02-12T08:02:48+00:00 Subject: [ruby-core:102467] [Ruby master Bug#17497] Ractor performance issue Issue #17497 has been updated by ko1 (Koichi Sasada). Status changed from Closed to Assigned keithrbennett (Keith Bennett) wrote in #note-17: > I've tested my benchmark against Ruby head, and performance with multiple cores seem to have degraded. Perhaps I have made an error in my approaches, I don't know. I will paste my results below. My OS is "Ubuntu 20.04.2 LTS" (Kubuntu). I confirmed with the following script ``` WORDS = Ractor.make_shareable File.readlines('/usr/share/dict/words').map(&:chomp).map(&:downcase).sort def try File.readlines(__dir__ + '/compar.c').each{|line| line.split.map(&:downcase).select { |text| WORDS.include? text } } end Warning[:experimental] = false require 'benchmark' Benchmark.bm{|x| x.report{ 4.times{try} } x.report{ 4.times.map{ Ractor.new{ try } }.each(&:take) } } __END__ user system total real 4.501388 0.001541 4.502929 ( 4.502980) 16.763446 0.000018 16.763464 ( 4.335964) ``` It compare with sequential 4 times `try` method and 4 times `try` methods on ractors in parallel. To compare with real, 4.5 vs 4.3 sec. It is not slow, but not first with 4 cores. The reason seems `WORDS.include? text`. I'll investigate more. ---------------------------------------- Bug #17497: Ractor performance issue https://bugs.ruby-lang.org/issues/17497#change-90356 * Author: marcandre (Marc-Andre Lafortune) * Status: Assigned * Priority: Normal * Assignee: ko1 (Koichi Sasada) * ruby -v: ruby 3.0.0p0 (2020-12-25 revision 95aff21468) [x86_64-darwin18] * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- There's a strange performance issue with Ractor (at least on MacOS, didn't run on other OS). I ran a benchmark doing 3 different types of work: * "fib": method calls (naive fibonacci calculation) * "cpu": `(0...1000).inject(:+)` * "sleep": call `sleep` I get the kind of results I was excepting for the `fib` and for sleeping, but the results for the "cpu" workload show a problem. It is so slow that my pure Ruby backport (using Threads) is 65x faster ���� on my Mac Pro (despite having 6 cores). Expected results would be 6x slower, so in that case Ractor is 400x slower than it should ���� On my MacBook (2 cores) the results are not as bad, the `cpu` workload is 3x faster with my pure-Ruby backport (only) instead of ~2x slower, so the factor is 6x too slow. ``` $ gem install backports Successfully installed backports-3.20.0 1 gem installed $ ruby ractor_test.rb :267: warning: Ractor is experimental, and the behavior may change in future versions of Ruby! Also there are many implementation issues. fib: 110 ms | cpu: 22900 ms | sleep: 206 ms $ B=t ruby ractor_test.rb Using pure Ruby implementation fib: 652 ms | cpu: 337 ms | sleep: 209 ms ``` Notice the `sleep` run takes similar time, which is good, and `fib` is ~6x faster on my 6-core CPU (and ~2x faster on my 2-core MacBook), again that's good as the pure ruby version uses Threads and thus runs with a single GVL. The `cpu` version is the problem. Script is here: https://gist.github.com/marcandre/bfed626e538a3d0fc7cad38dc026cf0e -- https://bugs.ruby-lang.org/ Unsubscribe: