Ruby parallel execution benchmark.

parallel_bench.rb

PARALLELISM = 16

def solve
  (1..5_000_000).inject(:+)
end

def solve_ractor
  ractors = PARALLELISM.times.map { Ractor.new { solve } }
  ractors.each { Ractor.select _1 }
end

def solve_thread
  threads = PARALLELISM.times.map { Thread.new { solve } }
  threads.each { _1.join }
end

def solve_process
  pids = PARALLELISM.times.map { fork { solve } }
  pids.each { Process.waitpid _1 }
end

require "benchmark"

Benchmark.bm do |x|
  x.report("process") { solve_process }
  x.report("thread") { solve_thread }
  x.report("ractor") { solve_ractor }
end

https://bugs.ruby-lang.org/issues/17497

This issue has been discussed above.