Simple threading

ruby-talk
1

Hi all,
I wanted to write a program that request stock quotes say every second. So I
started to write a thread like this:

  require 'rubygems'
  require 'yahoofinance'

  thread=Thread.new do
    YahooFinance::get_historical_quotes_days( 'goog', 10 ) do |row|
      puts "YHOO,#{row.join(',')}"
    end
  end

When I run this I don't get any results. Which is really weird. Got all the
gems and so on.
But when I do the same code run in IRB it works! without any surprises. I
don't get it. Really.

Thanks for any help.

Chris

2

Not sure, but adding 'thread.join' to the end might help.

···

On Tue, Jun 9, 2009 at 4:36 PM, Christoph Jasinski<christoph.jasinski@googlemail.com> wrote:

Hi all,
I wanted to write a program that request stock quotes say every second. So I
started to write a thread like this:

require 'rubygems'
require 'yahoofinance'

thread=Thread.new do
YahooFinance::get_historical_quotes_days( 'goog', 10 ) do |row|
puts "YHOO,#{row.join(',')}"
end
end

When I run this I don't get any results. Which is really weird. Got all the
gems and so on.
But when I do the same code run in IRB it works! without any surprises. I
don't get it. Really.

Thanks for any help.

Chris

--
Vikhyat Korrapati

3

Thanks,
it works; I don't know why, but it works

Cheers,

Chris

4

I know why it work. :slight_smile: Let me explain:

1. Your code splits into two threads (the main Thread Ruby started your program in and the one you created to talk to YahooFinance in)
2. After you have the two Threads, they both begin working (trading off time)
3. Your YahooFinance Thread probably starts talking over the network
4. However, your main Thread runs off the end of your file and when that happens, Ruby exits (killing the unfinished YahooFinance Thread)

Thus, Vikhyat had you add a line that asked the main Thread to join() or wait on the YahooFinance Thread to finish. That call won't return until the second Thread ends, so Ruby will wait to exit.

Of course, that means the second Thread doesn't really do anything for us in this case. But if you are launching a bunch of them or continuing to work in the main Thread, there will be benefits.

Hope that helps.

James Edward Gray II

···

On Jun 9, 2009, at 7:28 AM, Christoph Jasinski wrote:

Thanks,
it works; I don't know why, but it works