Robert Klemme
1/25/2006 8:25:00 AM
Russell Fulton wrote:
> Is there a way to ensure that a particular variable really is local
> to a thread block? I have a problem with a threaded program that
> would be explained if one of the local variable was actually global.
> I've checked everything I can think of...
>
> I miss my and local from perl which allowed me to explicitly control
> the scope of variables.
A typical problem with threads can be nicely illustrated with this:
09:21:51 [~]: ruby -e 'th=[]
> for i in 0 .. 5
> th << Thread.new do
> sleep(rand(5))
> puts i
> end
> end
> th.each {|t| t.join}
> '
2
5
5
5
5
5
09:22:21 [~]:
Problem here is that all threads share the local var 'i'. Solution:
09:22:21 [~]: ruby -e 'th=[]
> for i in 0 .. 5
> th << Thread.new(i) do |x|
> sleep(rand(5))
> puts x
> end
> end
> th.each {|t| t.join}'
0
1
5
4
2
3
I.e. provide value(s) as arguments to Thread.new and receive them as block
parameter(s) with different name(s).
HTH
Kind regards
robert