From: Joel VanderWerf <vjoel@...>
Date: 2004-01-17T09:52:06+09:00
Subject: drb server efficiency while running in irb


I've noticed that a drb server running in irb handles requests at a 
different rate depending on whether the main irb thread is running 
separately or has joined the drb thread. It's *much* slower as a 
separate thread. Typically the difference is about 1000 req/sec vs. 3 
req./sec. That is puzzling to me because the irb thread isn't doing 
anything but waiting for input. Both threads are priority 0, not that it 
should matter.

The example is based on the Pickaxe drb example--see below. My ruby 
version is:

$ ruby -v
ruby 1.9.0 (2004-01-08) [i686-linux]

The really *bizarre* behavior is that if I make the irb thread (the one 
that's running alongside the drb thread) do some work, like:

irb(main):019:0> 500000.times {10**100; 0}

then the server gets *faster*, up to 15-20 req/sec.

If the irb thread sleeps, then the server gets up to 600-700 req/sec 
(which makes some sense).

Increasing the DRb.thread.priority helps a bit (up to 15 req/sec)

Any theories? Suggestions?

----

==== paste this into irb, with or without the last line: ====
==== server.rb ====
require 'drb'

class TestServer
   def doit
     "Hello, Distributed World"
   end
end

aServerObject = TestServer.new
DRb.start_service('druby://localhost:9000', aServerObject)
DRb.thread.join # Without this line, drb service is much slower
================

==== run this as script or from irb ====
==== client.rb ====
require 'drb'
DRb.start_service()
obj = DRbObject.new(nil, 'druby://localhost:9000')

n = 1000

z0 = Time.now
n.times do
   obj.doit
end
z1 = Time.now

puts "Elapsed time: #{z1-z0}", "Rate: #{n/(z1-z0)} requests per second"
================