From: Mark Probert <probertm@...>
Date: 2002-04-13T04:05:40+09:00
Subject: confused about threads


Hi, again.

I am a little confused about threads and scope.  Here is a simple version
of what I want to do (the real version involves getting data via a telnet
session).

There is a class that gathers data (Bob) and I want it to go into an array
for post processing.  So there is a method load() that takes the array and
puts some data in.  It works okay by itself.  However, when I run this with
threading, the out[] has gets its keys, but the arrays are empty.

I am doing something wrong.  Can anyone help me out here?


(The example is modified from the Pick Axe book... thanks Dave and Andy)

-------

class Bob
     def load(n,arr)
       n.times do
         arr.push(n)
       end
     end
end

count = 0
arr = Array.new
out = Hash.new

10.times do |i|
   out[i] = Array.new

   arr[i] = Thread.new {
     sleep(rand(0)/10.0)
     b = Bob.new
     b.load(count,out[i])
   }
end

arr.each { |t| t.join }
out.keys.each { |v| puts "#{v} --> #{out[v]}" }

---------------------

[PROBERTM-2] ruby > irb -r threads.rb
5 -->
0 -->
6 -->
1 -->
7 -->
2 -->
8 -->
3 -->
9 -->
4 -->
irb(main):001:0> h = {}
{}
irb(main):002:0> h[3] = Array.new
[]
irb(main):003:0> b = Bob.new
#<Bob:0xa0af388>
irb(main):004:0> b.load(3,h[3])
3
irb(main):005:0> h
{3=>[3, 3, 3]}
irb(main):006:0> exit
[PROBERTM-2] ruby > ruby -v
ruby 1.6.6 (2001-12-26) [i686-cygwin]


TIA,



-mark.