Hi!
I wrote a little ruby script to measure Ruby/JRuby performance in
different interpreters/platforms: a script to compute the N:th prime.
I guessed that it should run almost equally fast on Windows and
Linux. But to my surprise there was a big difference. The same
computation with JRuby (the 100_000:th prime) took:
Linux: 11 seconds
Windows: 34 seconds
I used two machine with exactly the same hardware: " Intel(R)
Core(TM)2 Quad CPU Q6600 @ 2.40GHz". One running Ubuntu 7.10, the
other Windows XP Professional. And I had almost the same Java version
too (I think):
-------------- Windows ---------------
c:\> java -version
java version "1.6.0_04"
Java(TM) SE Runtime Environment (build 1.6.0_04-b12)
Java HotSpot(TM) Client VM (build 10.0-b19, mixed mode, sharing)
-------------- Linux ---------------
% java -version
java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Server VM (build 1.6.0_03-b05, mixed mode)
--------------------------------
To compare the Java versions I also rewrote the algorithm in Java, and
then they were equally fast on Windows and Ubuntu. But when I run my
ruby-script in JRuby Linux is three times faster.
Can you explain this to me? I don't understand the reason for this difference.
In both cases I use r5863 of JRuby, built locally on each machine.
/Johan Holmberg
I attach my script in case it matters:
-----------------------------------------
#!/usr/local/bin/ruby
require "monitor"
def is_prime(i)
d = 3
while d*d <= i
if i % d == 0
return false
end
d += 2
end
return true
end
def nth_prime(n)
i = 1
count = 1
while count != n
i += 2
if is_prime(i)
count += 1
end
end
return i
end
threads = []
threads.extend(MonitorMixin)
t1 = Time.now
for str in ARGV
threads << Thread.new(str) do |str2|
if str2 == "sleep"
sleep(5)
threads.synchronize do
puts "[%f] sleep done " % [
(Time.now - t1),
]
end
else
x2 = str2.to_i
nth = nth_prime(x2)
threads.synchronize do
puts "[%f] %d ---> %d" % [
(Time.now - t1),
x2,
nth,
]
end
end
end
end
for t in threads
t.join
end
puts "finishing ..."
-----------------------------------------
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