Threads vs Async Ruby

async.rb

require "async"

CONCURRENCY = 1000
ITERATIONS = 100

def work
  Async do |task|
    CONCURRENCY.times do
      task.async do
        sleep 1
      end
    end
  end
end

def duration
  start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  work
  Process.clock_gettime(Process::CLOCK_MONOTONIC) - start
end

def average
  ITERATIONS.times.sum {
    duration
  }.fdiv(ITERATIONS)
end

puts average # => 1.01772911996115

thread.rb

CONCURRENCY = 1000
ITERATIONS = 100

def work
  CONCURRENCY.times.map {
    Thread.new do
      sleep 1
    end
  }.each(&:join)
end

def duration
  start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  work
  Process.clock_gettime(Process::CLOCK_MONOTONIC) - start
end

def average
  ITERATIONS.times.sum {
    duration
  }.fdiv(ITERATIONS)
end

puts average # => 1.045861059986055

You should test real world case, like one event loop creating lots of fibers, rather than creating lots of event loops.

@bruno- thanks for catching my math mistakes 🙊 .

I'm not sure if this is the right way to look at it. I can't prove your math wrong,

In general, I'm nervous when there's a variable that I can arbitrarily change to get different (comparative) results. It makes me worried that I've gamed my own microbenchmark.

Not sure if you've seen but I've done a bunch of work in the space of trying to ensure a benchmark result are actually valid

• Take a look at comparative histograms and statistical significance checks https://github.com/zombocom/derailed_benchmarks#i-made-a-patch-to-to-rails-how-can-i-tell-if-it-made-my-rails-app-faster-and-test-for-statistical-significance
• Not specifically performance but about tuning a system that varies when number inputs are changed https://www.schneems.com/2020/07/08/a-fast-car-needs-good-brakes-how-we-added-client-rate-throttling-to-the-platform-api-gem/

My conclusion is that the average request duration for threads is 0.2225s or about 11% overhead on average.

That's the average across 200 runs. Each run does 1000 operations which is what I was dividing by (if that makes sense).

I've seen the noah article ages ago, but forgotten about it (thanks for the reminder). The code is here https://github.com/noahgibbs/fiber_basic_benchmarks/tree/master/benchmarks that file got renamed it looks like.